2012 GMC Sierra Owners Manual

setting to change.

. Activating the Manual Trailer

Brake Apply lever.

. Connecting a trailer equipped

with electric trailer brakes.

All DIC warning and service messages must first be acknowledged by the driver by pressing the odometer trip stem or the DIC Vehicle Information button (if equipped) before the Trailer Brake Display Page can be displayed and Trailer Gain can be adjusted.

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9-102

Driving and Operating

TRAILER GAIN: This setting is displayed any time the Trailer Brake Display Page is active. This setting can be adjusted from 0.0 to 10.0
with either a trailer connected or disconnected. To adjust the Trailer Gain, press one of the Trailer Gain adjustment buttons located on the Trailer Brake Control Panel. Press and hold a gain button to cause the Trailer Gain to continuously adjust. To turn the output to the trailer off, adjust the Trailer Gain setting to 0.0 (zero). 0.0 (zero) gain is the factory default setting. To properly adjust trailer gain, see “Trailer Gain Adjustment Procedure” later in this section. TRAILER OUTPUT: This is displayed any time a trailer with electric brakes is connected. Output to the electric brakes is based on the amount of vehicle braking present and relative to the Trailer Gain setting. Output is displayed from 0 to 10 bars for each gain setting.

Non-hybrid vehicles with Trailer Sway Control (TSC) or Hill Start Assist (HSA), output to the electric trailer brakes may be displayed when the systems are active. See Trailer Sway Control (TSC) on page 9‑105 and Hill Start Assist (HSA) on page 9‑54. The Trailer Output will indicate “- - - - - -” on the Trailer Brake Display Page whenever the following occur: . No trailer is connected . A trailer without electric brakes is connected (no DIC message is displayed)

. A trailer with electric brakes

has become disconnected (a CHECK TRAILER WIRING message will also be displayed on the DIC) There is a fault present in the wiring to the electric trailer brakes (a CHECK TRAILER WIRING message will also be displayed on the DIC)

There is a fault in the ITBC system (a SERVICE TRAILER BRAKE SYSTEM message will also be displayed in the DIC)

Manual Trailer Brake Apply The Manual Trailer Brake Apply Lever is located on the Trailer Brake Control Panel and is used to apply the trailer’s electric brakes independent of the vehicle’s brakes. This lever is used in the Trailer Gain Adjustment Procedure to properly adjust the power output to the trailer brakes. Sliding the lever to the left will apply only the trailer brakes. The power output to the trailer is indicated in the Trailer Brake Display Page on the DIC. If the vehicle’s service brakes are applied while using the Manual Trailer Brake Apply Lever, the trailer output power will be the greater of the two. The trailer's and the vehicle's brake lamps will come on when either vehicle braking or manual trailer brakes are applied.

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Driving and Operating

9-103

Trailer Gain Adjustment Procedure Trailer Gain should be set for a specific trailering condition and must be adjusted any time vehicle loading, trailer loading, or road surface conditions change. Setting the Trailer Gain properly is needed for the best trailer stopping performance. A trailer that is over-gained may result in locked trailer brakes. A trailer that is under-gained may result in not enough trailer braking. Both of these conditions may result in poorer stopping and stability of the vehicle and trailer. Use the following procedure to correctly adjust Trailer Gain for each towing condition: 1. Make sure the trailer brakes are

in proper working condition.

electrical connections. See Vehicle Load Limits on page 9‑16 for more information. 3. After the electrical connection is made to a trailer equipped with electric brakes:

A TRAILER CONNECTED message will be briefly displayed on the DIC. The Trailer Brake Display Page will appear on the DIC showing TRAILER GAIN and TRAILER OUTPUT. In the Trailer Output display on the DIC, “- - - - - -” will disappear if there is no error present. Connecting a trailer without electric brakes will not clear the six dashed lines.

2. Connect a properly loaded trailer

4. Adjust the Trailer Gain by using

to the vehicle and make all necessary mechanical and

the gain adjustment (+ / -) buttons on the Trailer Brake Control Panel.

5. Drive the vehicle with the trailer attached on a level road surface representative of the towing condition and free of traffic at about 32 to 40 km/h (20 to 25 mph) and fully apply the Manual Trailer Brake Apply Lever. Adjusting trailer gain at speeds lower than 32 to 40 km/h (20 to 25 mph) may result in an incorrect gain setting.

6. Adjust the Trailer Gain to just

below the point of trailer wheel lock-up, indicated by trailer wheel squeal or tire smoke when a trailer wheel locks. Trailer wheel lock-up may not occur if towing a heavily loaded trailer. In this case, adjust the Trailer Gain to the highest allowable setting for the towing condition.

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Driving and Operating

7. Re-adjust Trailer Gain any time

vehicle loading, trailer loading or road surface conditions change or if trailer wheel lock-up is noticed at any time while towing.

Other ITBC-Related DIC Messages In addition to displaying TRAILER GAIN and TRAILER OUTPUT through the DIC, trailer connection and ITBC system status are displayed on the DIC. TRAILER CONNECTED: This message will be briefly displayed when a trailer with electric brakes is first connected to the vehicle. This message will automatically turn off in about 10 seconds. The driver can also acknowledge this message before it automatically turns off. CHECK TRAILER WIRING: This message will be displayed if: 1. The ITBC system first

determines connection to a trailer with electric brakes and then the trailer harness becomes disconnected from the vehicle.

If the disconnect occurs while the vehicle is stationary, this message will automatically turn off in about 30 seconds. This message will also turn off if the driver acknowledges this message or if the trailer harness is re-connected. If the disconnect occurs while the vehicle is moving, this message will continue until the ignition is turned off. This message will also turn off if the driver acknowledges this message or if the trailer harness is re-connected.

2. There is an electrical fault in

the wiring to the electric trailer brakes. This message will continue as long as there is an electrical fault in the trailer wiring. This message will also turn off if the driver acknowledges this message.

To determine if the electrical fault is on the vehicle side or trailer side of the trailer wiring harness connection, do the following: 1. Disconnect the trailer wiring

harness from the vehicle.

2. Turn the ignition off. 3. Wait 10 seconds, then turn the

4.

ignition back to RUN. If the CHECK TRAILER WIRING message re-appears, the electrical fault is on the vehicle side. If the CHECK TRAILER WIRING message only re-appears when connecting the trailer wiring harness to the vehicle, the electrical fault is on the trailer side.

SERVICE TRAILER BRAKE SYSTEM: This message will be displayed when there is a problem with the ITBC system. If this message persists over multiple ignition cycles, there is a problem with the ITBC system. Take the

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Driving and Operating

9-105

vehicle to an authorized GM dealer to have the ITBC system diagnosed and repaired. If either the CHECK TRAILER WIRING or SERVICE TRAILER BRAKE SYSTEM message is displayed while driving the vehicle, power is no longer available to the trailer brakes. When traffic conditions allow, carefully pull the vehicle over to the side of the road and turn the ignition off. Check the wiring connection to the trailer and turn the ignition back on. If either of these messages continues, either the vehicle or trailer needs service. An authorized GM dealer may be able to diagnose and repair problems with the trailer. However, any diagnosis and repair of the trailer is not covered under the vehicle warranty. Please contact your trailer dealer for assistance with trailer repairs and trailer warranty information.

Trailer Sway Control (TSC) Non-hybrid vehicles with StabiliTrak have a Trailer Sway Control (TSC) feature. If the vehicle is towing a trailer and the system detects that the trailer is swaying, the vehicle brakes are applied without the driver pressing the brake pedal. If the vehicle is equipped with the Integrated Trailer Brake Control (ITBC) system, StabiliTrak may also apply the trailer brakes. The TCS/ StabiliTrak warning light will flash on the instrument panel cluster to notify the driver to reduce speed. If the trailer continues to sway, StabiliTrak will reduce engine torque to help slow the vehicle. See StabiliTrak® System on page 9‑55 for more information. Adding non‐dealer accessories can affect the vehicle performance. See Accessories and Modifications on page 10‑3 for more information.

Conversions and Add-Ons

Add-On Electrical Equipment Notice: Do not add anything electrical to the vehicle unless you check with your dealer first. Some electrical equipment can damage the vehicle and the damage would not be covered by the vehicle's warranty. Some add-on electrical equipment can keep other components from working as they should. Add-on equipment can drain the vehicle's 12‐volt battery, even if the vehicle is not operating. The vehicle has an airbag system. Before attempting to add anything electrical to the vehicle, see Servicing the Airbag-Equipped Vehicle on page 3‑36 and Adding Equipment to the Airbag-Equipped Vehicle on page 3‑37.

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Driving and Operating

Adding a Snow Plow or Similar Equipment Before installing a snow plow on the vehicle, here are some things you need to know: Notice: If the vehicle does not have the snow plow prep package, adding a plow can damage the vehicle, and the repairs would not be covered by warranty. Unless the vehicle was built to carry a snow plow, do not add one to the vehicle. If the vehicle has the snow plow prep package, called RPO VYU, then the payload the vehicle can carry will be reduced when a snow plow is installed. The vehicle can be damaged if either the front or rear axle ratings or the Gross Vehicle Weight Rating (GVWR) are exceeded.

Some vehicles are built with a special snow plow prep package, called RPO VYU. If the vehicle has this option, you can add a plow to it, provided certain weights, such as the weights on the vehicle's axles and the Gross Vehicle Weight Rating (GVWR), are not exceeded. The plow the vehicle can carry depends on many things, such as:

The options the vehicle came with, and the weight of those options. The weight and number of passengers intended to be carried. The weight of items added to the vehicle, like a tool box or truck cap. The total weight of any additional cargo intended to be carried.

Say, for example, you have a 318 kg (700 lb) snow plow. The total weight of all occupants and cargo inside the cab should not exceed 135 kg

(300 lb). This means that you may only be able to carry one passenger. But, even this may be too much if there is other equipment already adding to the weight of the vehicle. Here are some guidelines for safely carrying a snow plow on the vehicle: . Make sure the weight on the front and rear axles does not exceed the axle rating for each. For the front axle, if more cargo or passengers must be carried, appropriate counter ballast must be installed rear of the rear axle. Counter ballast must be properly secured so it will not move during driving. Follow the snow plow manufacturer's recommendations regarding rear ballast. Rear ballast may be required to ensure a proper front and rear weight distribution ratio, even though the actual weight at the front axle may be less than the front axle rating.

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The snow plow manufacturer or installer can assist you in determining the amount of rear ballast required, to help make sure the snowplow/vehicle combination does not exceed the GVW rating, the front and rear axle ratings, and the front and rear weight distribution ratio. The total vehicle must not exceed the GVW rating.

Front axle reserve capacity is the difference between the Gross Axle Weight Rating (GAWR) and the front axle weight of the vehicle with full fuel and passengers. Basically, it is the amount of weight that can be added to the front axle before reaching the front GAWR. The front axle reserve capacity for the vehicle can be found in the lower right corner of the Certification/Tire label, as shown.

Driving and Operating

9-107

In order to calculate the amount of weight any front accessory, such as a snow plow, is adding to the front axle, use the following formula:

United States

Canada

(W x (A + W.B.)) /W.B.= Weight the accessory is adding to the front axle. Where:

W = Weight of added accessory A = Distance that the accessory is in front of the front axle W.B. = Vehicle Wheelbase

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Driving and Operating

For example, adding a 318 kg (700 lb) snow plow actually adds more than 318 kg (700 lb) to the front axle. Using the formula, if the snow plow is 122 cm (4 ft) in front of the front axle and the wheel base is 305 cm (10 ft), then:

W = 318 kg (700 lb) A = 122 cm (4 ft) W.B. = 305 cm (10 ft)

(W x (A + W.B.))/W.B. = (318 x (122 + 305))/305 = 445 kg (980 lbs) So, if the front axle reserve capacity is more than 445 kg (980 lbs), the snow plow could be added without exceeding the front GAWR. Heavier equipment can be added on the front of the vehicle if it is compensated for by carrying fewer passengers, less cargo, or by positioning cargo toward the rear. This has the effect of reducing the load on the front. However, the front GAWR, rear GAWR, and the Gross Vehicle Weight Rating (GVWR) must never be exceeded.

{ WARNING

On some vehicles that have certain front mounted equipment, such as a snow plow, it may be possible to load the front axle to the front gross axle weight rating (GAWR) but not have enough weight on the rear axle to have proper braking performance. If the brakes cannot work properly, you could have a crash. To help the brakes work properly when a snow plow is installed, always follow the snow plow manufacturer or installer's recommendation for rear ballast to ensure a proper front and rear weight distribution ratio, even though the actual front weight may be less than the front GAWR, and the total vehicle weight is less than the gross vehicle weight rating (GVWR). Maintaining a proper front and

(Continued)

WARNING (Continued)

rear weight distribution ratio is necessary to provide proper braking performance.

Total vehicle reserve capacity is the difference between the GVWR and the weight of the truck with full fuel and passengers. It is the amount of weight that can be added to the vehicle before reaching the GVWR. Keep in mind that reserve capacity numbers are intended as a guide when selecting the amount of equipment or cargo the truck can carry. If unsure of the vehicle's front, rear, or total weight, go to a weigh station and weigh the vehicle. Your dealer can also help with this. The total vehicle reserve capacity for the vehicle can be found in the lower right corner of the Certification/Tire label as shown previously.

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Driving and Operating

9-109

See your dealer for additional advice and information about using a snow plow on the vehicle. Also, see Vehicle Load Limits on page 9‑16. Emergency Roof Lamp Provisions Vehicles with the RPO VYU snow plow prep package also have an emergency roof lamp provision package, RPO TRW. Wiring for the emergency roof lamp is provided above the overhead console. See Auxiliary Roof-Mounted Lamp on page 6‑6 for switch location.

Pickup Conversion to Chassis Cab We are aware that some vehicle owners might consider having the pickup box removed and a commercial or recreational body installed. Owners should be aware that, as manufactured, there are differences between a chassis cab and a pickup with the box removed which could affect vehicle safety. The components necessary to adapt a pickup to permit its safe use with a specialized body should be installed by the body builder.

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Driving and Operating

2 NOTES

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Vehicle Care

General Information

General Information . . . . . . . . . . 10-2
California Proposition

65 Warning . . . . . . . . . . . . . . . . . 10-3

California Perchlorate

Materials Requirements . . . . 10-3

Accessories and

Modifications . . . . . . . . . . . . . . . 10-3

Vehicle Checks Doing Your Own

Service Work . . . . . . . . . . . . . . . 10-4
Hood . . . . . . . . . . . . . . . . . . . . . . . . 10-5
Engine Compartment

Overview . . . . . . . . . . . . . . . . . . . 10-6
Engine Oil . . . . . . . . . . . . . . . . . . . 10-7
Engine Oil Life System . . . . . 10-10
Automatic Transmission Fluid

(4-Speed Transmission) . . . 10-11

Automatic Transmission

Fluid (6-Speed Transmission) . . . . . . . . . . . . . 10-14
Engine Air Cleaner/Filter . . . . 10-17
Cooling System . . . . . . . . . . . . 10-18
Engine Coolant . . . . . . . . . . . . . 10-19
Engine Overheating . . . . . . . . 10-22

Overheated Engine

Protection Operating Mode . . . . . . . . . . . 10-24
Engine Fan . . . . . . . . . . . . . . . . . 10-24
Power Steering Fluid . . . . . . . 10-25
Washer Fluid . . . . . . . . . . . . . . . 10-26
Brakes . . . . . . . . . . . . . . . . . . . . . 10-27
Brake Fluid . . . . . . . . . . . . . . . . . 10-28
Battery . . . . . . . . . . . . . . . . . . . . . 10-30
Four-Wheel Drive . . . . . . . . . . . 10-30
Front Axle . . . . . . . . . . . . . . . . . . 10-31
Rear Axle . . . . . . . . . . . . . . . . . . 10-32
Noise Control System . . . . . . 10-34
Starter Switch Check . . . . . . . 10-35
Automatic Transmission Shift

Lock Control Function Check . . . . . . . . . . . . . . . . . . . . . 10-35

Ignition Transmission Lock

Check . . . . . . . . . . . . . . . . . . . . . 10-35

Park Brake and P (Park)

Mechanism Check . . . . . . . . 10-36

Wiper Blade

Replacement . . . . . . . . . . . . . . 10-36
Glass Replacement . . . . . . . . 10-37

Headlamp Aiming

Headlamp Aiming . . . . . . . . . . 10-37

Vehicle Care

10-1

Bulb Replacement

Bulb Replacement . . . . . . . . . . 10-39
Halogen Bulbs . . . . . . . . . . . . . . 10-39
Headlamps, Front Turn

Signal, Sidemarker, and Parking Lamps . . . . . . . . . . . . 10-39

Pick-Up Box Identification

and Fender Marker Lamps . . . . . . . . . . . . . . . . . . . . 10-40

Taillamps (Chassis Cab

Models) . . . . . . . . . . . . . . . . . . . 10-40

Taillamps, Turn Signal,

Stoplamps, and Back-Up Lamps . . . . . . . . . . . . . . . . . . . . 10-41

Center High-Mounted

Stoplamp (CHMSL) and Cargo Lamp . . . . . . . . . . . . . . 10-42
License Plate Lamp . . . . . . . . 10-42
Replacement Bulbs . . . . . . . . . 10-43

Electrical System

Electrical System

Overload . . . . . . . . . . . . . . . . . . 10-43

Fuses and Circuit

Breakers . . . . . . . . . . . . . . . . . . 10-44

Engine Compartment Fuse

Block . . . . . . . . . . . . . . . . . . . . . 10-44

Instrument Panel Fuse

Block . . . . . . . . . . . . . . . . . . . . . 10-48

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10-2

Vehicle Care

Wheels and Tires

Tires . . . . . . . . . . . . . . . . . . . . . . . . 10-50
Tire Sidewall Labeling . . . . . . 10-52
Tire Designations . . . . . . . . . . . 10-54
Tire Terminology and

Definitions . . . . . . . . . . . . . . . . 10-55
Tire Pressure . . . . . . . . . . . . . . . 10-58
Tire Pressure for High-Speed

Operation . . . . . . . . . . . . . . . . . 10-60

Tire Pressure Monitor

System . . . . . . . . . . . . . . . . . . . 10-60

Tire Pressure Monitor

Operation . . . . . . . . . . . . . . . . . 10-62
Tire Inspection . . . . . . . . . . . . . . 10-65
Tire Rotation . . . . . . . . . . . . . . . 10-65
Dual Tire Rotation . . . . . . . . . . 10-67
When It Is Time for New

Tires . . . . . . . . . . . . . . . . . . . . . . 10-68
Buying New Tires . . . . . . . . . . . 10-68
Different Size Tires and

Wheels . . . . . . . . . . . . . . . . . . . 10-70

General Information For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people. Genuine GM parts have one of these marks:

Uniform Tire Quality

Grading . . . . . . . . . . . . . . . . . . . 10-70

Wheel Alignment and Tire

Balance . . . . . . . . . . . . . . . . . . . 10-72
Wheel Replacement . . . . . . . . 10-72
Tire Chains . . . . . . . . . . . . . . . . . 10-74
If a Tire Goes Flat . . . . . . . . . . 10-75
Tire Changing . . . . . . . . . . . . . . 10-76
Full-Size Spare Tire . . . . . . . . 10-87

Jump Starting

Jump Starting . . . . . . . . . . . . . . 10-88

Towing

Towing the Vehicle . . . . . . . . . 10-93
Recreational Vehicle

Towing . . . . . . . . . . . . . . . . . . . . 10-93

Appearance Care

Exterior Care . . . . . . . . . . . . . . . 10-98
Interior Care . . . . . . . . . . . . . . . 10-101
Floor Mats . . . . . . . . . . . . . . . . 10-104

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California Proposition 65 Warning Most motor vehicles, including this one, contain and/or emit chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. Engine exhaust, many parts and systems, many fluids, and some component wear by-products contain and/or emit these chemicals.

California Perchlorate Materials Requirements Certain types of automotive applications, such as airbag initiators, safety belt pretensioners, and lithium batteries contained in Remote Keyless Entry transmitters, may contain perchlorate materials. Special handling may be necessary. For additional information, see www.dtsc.ca.gov/hazardouswaste/ perchlorate.

Vehicle Care

10-3

Accessories and Modifications Adding non‐dealer accessories or making modifications to the vehicle can affect vehicle performance and safety, including such things as airbags, braking, stability, ride and handling, emissions systems, aerodynamics, durability, and electronic systems like antilock brakes, traction control, and stability control. These accessories or modifications could even cause malfunction or damage not covered by the vehicle warranty.

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10-4

Vehicle Care

Damage to vehicle components resulting from modifications or the installation or use of non‐GM certified parts, including control module or software modifications, is not covered under the terms of the vehicle warranty and may affect remaining warranty coverage for affected parts. GM Accessories are designed to complement and function with other systems on the vehicle. See your dealer to accessorize the vehicle using genuine GM Accessories installed by a dealer technician. Also, see Adding Equipment to the Airbag-Equipped Vehicle on page 3‑37.

Vehicle Checks

Doing Your Own Service Work If the vehicle is a hybrid, see the hybrid supplement for more information.

{ WARNING

It can be dangerous to work on your vehicle if you do not have the proper knowledge, service manual, tools, or parts. Always follow owner manual procedures and consult the service manual for your vehicle before doing any service work.

If doing some of your own service work, use the proper service manual. It tells you much more about how to service the vehicle than this manual can. To order the proper service manual, see Service Publications Ordering Information on page 13‑16. This vehicle has an airbag system. Before attempting to do your own service work, see Airbag System Check on page 3‑38. Keep a record with all parts receipts and list the mileage and the date of any service work performed. See Maintenance Records on page 11‑16.

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Hood To open the hood:

1. Pull the handle with this symbol

on it. It is located inside the vehicle to the lower left of the steering wheel.

2. Then go to the front of the

vehicle and locate the secondary hood release, near the center of the grille.

Vehicle Care

10-5

3. Push the secondary hood

release to the right.

4. Lift the hood.

Before closing the hood, be sure all the filler caps are on properly. Then bring the hood from full open to within 152 mm (6 in) from the closed position, pause, then push the front center of the hood with a swift, firm motion to fully close the hood.

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10-6

Vehicle Care

Engine Compartment Overview

5.3 L V8 Engine Shown (4.3 L V6 Engine, 4.8 L V8 Engine, 6.0 L V8 Engine, and 6.2 L V8 Engine Similar)

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A. Engine Air Cleaner/Filter on

H. Engine Oil Dipstick (Out of

page 10‑17.

B. Coolant Surge Tank and

Pressure Cap. See Cooling System on page 10‑18.

C. Positive (+) Terminal. See Jump

Starting on page 10‑88. D. Battery on page 10‑30. E. Remote Negative (−) Terminal

(Out of View). See Jump Starting on page 10‑88. F. Automatic Transmission

Dipstick (Out of View). See “Checking the Fluid Level” under Automatic Transmission Fluid (4-Speed Transmission) on page 10‑11 or Automatic Transmission Fluid (6-Speed Transmission) on page 10‑14.

View). See “Checking Engine Oil” under Engine Oil on page 10‑7. Engine Cooling Fan (Out of View). See Cooling System on page 10‑18.

I.

J. Power Steering Fluid Reservoir.

See Power Steering Fluid on page 10‑25.

K. Brake Master Cylinder

Reservoir. See Brake Fluid on page 10‑28.

L. Engine Compartment Fuse

Block on page 10‑44.

M. Windshield Washer Fluid

Reservoir. See “Adding Washer Fluid” under Washer Fluid on page 10‑26.

G. Engine Oil Fill Cap. See “When

to Add Engine Oil” under Engine Oil on page 10‑7.

If the vehicle has a diesel engine and/or an Allison Transmission, see the Duramax Diesel Supplement.

Vehicle Care

10-7

Engine Oil For diesel engine vehicles, see “Engine Oil” in the Duramax Diesel Supplement. To ensure proper engine performance and long life, careful attention must be paid to engine oil. Following these simple, but important steps will help protect your investment: . Always use engine oil approved to the proper specification and of the proper viscosity grade. See “Selecting the Right Engine Oil” in this section.

. Check the engine oil level regularly and maintain the proper oil level. See “Checking Engine Oil” and “When to Add Engine Oil” in this section.

. Change the engine oil at the

appropriate time. See Engine Oil Life System on page 10‑10. . Always dispose of engine oil

properly. See “What to Do with Used Oil” in this section.

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10-8

Vehicle Care

Checking Engine Oil It is a good idea to check the engine oil level at each fuel fill. In order to get an accurate reading, the vehicle must be on level ground. The engine oil dipstick handle is a yellow loop. See Engine Compartment Overview on page 10‑6 for the location of the engine oil dipstick. Obtaining an accurate oil level reading is essential: 1.

If the engine has been running recently, turn off the engine and allow several minutes for the oil to drain back into the oil pan. Checking the oil level too soon after engine shutoff will not provide an accurate oil level reading.

2. Pull out the dipstick and clean

it with a paper towel or cloth, then push it back in all the way. Remove it again, keeping the tip down, and check the level.

When to Add Engine Oil

If the oil is below the cross-hatched area at the tip of the dipstick, add 1 L (1 qt) of the recommended oil and then recheck the level. See “Selecting the Right Engine Oil” in this section for an explanation of what kind of oil to use. For engine oil crankcase capacity, see Capacities and Specifications on page 12‑2. Notice: Do not add too much oil. Oil levels above or below the acceptable operating range shown on the dipstick are harmful to the engine. If you find that you have an oil level above the operating range, i.e., the engine

has so much oil that the oil level gets above the cross-hatched area that shows the proper operating range, the engine could be damaged. You should drain out the excess oil or limit driving of the vehicle and seek a service professional to remove the excess amount of oil. See Engine Compartment Overview on page 10‑6 for the location of the engine oil fill cap. Add enough oil to put the level somewhere in the proper operating range. Push the dipstick all the way back in when through. Selecting the Right Engine Oil Selecting the right engine oil depends on both the proper oil specification and viscosity grade. See Recommended Fluids and Lubricants on page 11‑12.

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Specification Use and ask for licensed engine oils with the dexos1™ approved certification mark. Engine oils meeting the requirements for the vehicle should have the dexos™1
approved certification mark. This certification mark indicates that the oil has been approved to the dexos1 specification.

Notice: Failure to use the recommended engine oil or equivalent can result in engine damage not covered by the vehicle warranty. Check with your dealer or service provider on whether the oil is approved to the dexos1 specification.

Viscosity Grade SAE 5W‐30 is the best viscosity grade for the vehicle. Do not use other viscosity grade oils such as SAE 10W‐30, 10W‐40, or 20W‐50. If in an area of extreme cold, where the temperature falls below −20°F (−29°C), an SAE 0W‐30 oil should be used. An oil of this viscosity grade will provide easier cold starting for the engine at extremely low temperatures. When selecting an oil of the appropriate viscosity grade, always select an oil that meets the dexos1 specification or equivalent. See “Specification” for more information. Engine Oil Additives/Engine Oil Flushes Do not add anything to the oil. The recommended oils with the dexos specification and displaying the dexos certification mark are all that is needed for good performance and engine protection.

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10-9

Engine oil system flushes are not recommended and could cause engine damage not covered by the vehicle warranty. What to Do with Used Oil Used engine oil contains certain elements that can be unhealthy for your skin and could even cause cancer. Do not let used oil stay on your skin for very long. Clean your skin and nails with soap and water, or a good hand cleaner. Wash or properly dispose of clothing or rags containing used engine oil. See the manufacturer's warnings about the use and disposal of oil products. Used oil can be a threat to the environment. If you change your own oil, be sure to drain all the oil from the filter before disposal. Never dispose of oil by putting it in the trash or pouring it on the ground, into sewers, or into streams or bodies of water. Recycle it by taking it to a place that collects used oil.

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10-10

Vehicle Care

Engine Oil Life System

When to Change Engine Oil This vehicle has a computer system that indicates when to change the engine oil and filter. This is based on a combination of factors which include engine revolutions, engine temperature, and miles driven. Based on driving conditions, the mileage at which an oil change is indicated can vary considerably. For the oil life system to work properly, the system must be reset every time the oil is changed. On some vehicles, when the system has calculated that oil life has been diminished, a CHANGE ENGINE OIL SOON message comes on to indicate that an oil change is necessary. See Engine Oil Messages on page 5‑42. Change the oil as soon as possible within the next 1 000 km (600 mi). It is possible that, if driving under the

best conditions, the oil life system might indicate that an oil change is not necessary for up to a year. The engine oil and filter must be changed at least once a year and, at this time, the system must be reset. For vehicles without the CHANGE ENGINE OIL SOON message, an oil change is needed when the OIL LIFE REMAINING percentage is near 0%. Your dealer has trained service people who will perform this work and reset the system. It is also important to check the oil regularly over the course of an oil drain interval and keep it at the proper level. If the system is ever reset accidentally, the oil must be changed at 5 000 km (3,000 mi) since the last oil change. Remember to reset the oil life system whenever the oil is changed.

How to Reset the Engine Oil Life System Reset the system whenever the engine oil is changed so that the system can calculate the next engine oil change. Always reset the engine oil life to 100% after every oil change. It will not reset itself. To reset the system on most vehicles: 1. Display the OIL LIFE

REMAINING on the DIC. If the vehicle does not have DIC buttons, the vehicle must be in P (Park) to access this display. See Driver Information Center (DIC) on page 5‑30.

2. Press and hold the SET/RESET

button on the DIC, or the trip odometer reset stem if the vehicle does not have DIC buttons, for more than five seconds. The oil life will change to 100%.

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On all vehicles, the Engine Oil Life System can be reset as follows: 1. Turn the ignition to ON/RUN with

the engine off.

2. Fully press the accelerator pedal

slowly three times within five seconds.

3. Display the OIL LIFE

REMAINING on the DIC. If the display shows 100%, the system is reset. See Driver Information Center (DIC) on page 5‑30.

If the vehicle has a CHANGE ENGINE OIL SOON message and it comes back on when the vehicle is started and/or the OIL LIFE REMAINING is near 0%, the engine oil life system has not been reset. Repeat the procedure.

Automatic Transmission Fluid (4-Speed Transmission)

When to Check and Change Automatic Transmission Fluid A good time to check the automatic transmission fluid level is when the engine oil is changed. Change the fluid and filter at the intervals listed in Maintenance Schedule on page 11‑3 and be sure to use the transmission fluid listed in Recommended Fluids and Lubricants on page 11‑12. How to Check Automatic Transmission Fluid Because this operation can be a little difficult, it may be best to have this done at the dealer service department. If not taken to the dealer, be sure to follow all the instructions here or a false reading on the dipstick could result.

Vehicle Care

10-11

Notice: Too much or too little fluid can damage the transmission. Too much can mean that some of the fluid could come out and fall on hot engine parts or exhaust system parts, starting a fire. Too little fluid could cause the transmission to overheat. Be sure to get an accurate reading if checking the transmission fluid. Wait at least 30 minutes before checking the transmission fluid level if you have been driving: . When outside temperatures are

above 32°C (90°F).

. At high speed for quite a while. In heavy traffic — especially in hot weather.

. While pulling a trailer. To get the right reading, the fluid should be at normal operating temperature, which is 82°C to 93°C (180°F to 200°F).

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10-12

Vehicle Care

Get the vehicle warmed up by driving about 24 km (15 miles) when outside temperatures are above 10°C (50°F). If it is colder than 10°C (50°F), drive the vehicle in 3 (Third) until the engine temperature gauge moves and then remains steady for 10 minutes. A cold fluid check can be made after the vehicle has been sitting for eight hours or more with the engine off, but this is used only as a reference. Let the engine run at idle for five minutes if outside temperatures are 10°C (50°F) or more. If it is colder than 10°C (50°F), the engine may have to idle longer. Should the fluid level be low during this cold check, the fluid must be checked when hot before adding fluid. Checking the fluid hot will give you a more accurate reading of the fluid level.

Checking the Fluid Level Prepare the vehicle as follows: 1. Park the vehicle on a level

place. Keep the engine running. 2. With the parking brake applied, place the shift lever in P (Park).

3. With your foot on the brake pedal, move the shift lever through each gear range, pausing for about three seconds in each range. Then, position the shift lever in P (Park).

4. Let the engine run at idle for

three minutes or more.

Then, without shutting off the engine, follow these steps:

1. Locate the transmission dipstick handle with this graphic which is located at the rear of the engine compartment, on the passenger side of the vehicle. See Engine Compartment Overview on page 10‑6 for more information on location.

2. Flip the handle up, then pull out

the dipstick and wipe it with a clean rag or paper towel.

3. Push it back in all the way, wait

three seconds and then pull it back out again.

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4. Check both sides of the dipstick,

and read the lower level. The fluid level must be in the COLD area, below the cross-hatched area, for a cold check or in the HOT or cross-hatched area for a hot check. Be sure to keep the dipstick pointed down to get an accurate reading. If the fluid level is in the acceptable range, push the dipstick back in all the way; then flip the handle down to lock the dipstick in place.

5.

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10-13

Notice: Use of the incorrect automatic transmission fluid may damage the vehicle, and the damages may not be covered by the vehicle warranty. Always use the automatic transmission fluid listed in Recommended Fluids and Lubricants on page 11‑12. . After adding fluid, recheck the fluid level as described under “How to Check Automatic Transmission Fluid,” earlier in this section.

. When the correct fluid level is

obtained, push the dipstick back in all the way; then flip the handle down to lock the dipstick in place.

Consistency of Readings Always check the fluid level at least twice using the procedure described previously. Consistency (repeatable readings) is important to maintaining proper fluid level. If readings are still inconsistent, contact the dealer. How to Add Automatic Transmission Fluid Refer to Recommended Fluids and Lubricants on page 11‑12 to determine what kind of transmission fluid to use. Using a funnel, add fluid down the transmission dipstick tube only after checking the transmission fluid while it is hot. A cold check is used only as a reference. If the fluid level is low, add only enough of the proper fluid to bring the level up to the HOT area for a hot check. It does not take much fluid, generally less than 0.5 Liter (1 Pint). Do not overfill.

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Vehicle Care

Automatic Transmission Fluid (6-Speed Transmission)

When to Check and Change Automatic Transmission Fluid It is usually not necessary to check the transmission fluid level. The only reason for fluid loss is a transmission leak or overheated transmission. If a small leak is suspected, then use the following checking procedures to check the fluid level. However, if there is a large leak, then it may be necessary to have the vehicle towed to a dealer service department and have it repaired before driving the vehicle further. Notice: Use of the incorrect automatic transmission fluid may damage the vehicle, and the damages may not be covered by the vehicle warranty. Always use the automatic transmission fluid listed in Recommended Fluids and Lubricants on page 11‑12.

Change the fluid and filter at the scheduled maintenance intervals listed in Maintenance Schedule on page 11‑3. Be sure to use the transmission fluid listed in Recommended Fluids and Lubricants on page 11‑12. How to Check Automatic Transmission Fluid Notice: Too much or too little fluid can damage the transmission. Too much can mean that some of the fluid could come out and fall on hot engine parts or exhaust system parts, starting a fire. Too little fluid could cause the transmission to overheat. Be sure to get an accurate reading if checking the transmission fluid.

Before checking the fluid level, prepare the vehicle as follows: 1. Start the engine and park the

vehicle on a level surface. Keep the engine running.

2. Apply the parking brake and

place the shift lever in P (Park).

3. With your foot on the brake pedal, move the shift lever through each gear range, pausing for about three seconds in each range. Then, move the shift lever back to P (Park).

4. Allow the engine to idle

(500 – 800 rpm) for at least 1 minute. Slowly release the brake pedal.

5. Keep the engine running and press the Trip/Fuel button or trip odometer reset stem until TRANS TEMP (Transmission Temperature) displays on the Driver Information Center (DIC).

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Vehicle Care

10-15

6. Using the TRANS TEMP

reading, determine and perform the appropriate check procedure. If the TRANS TEMP reading is not within the required temperature ranges, allow the vehicle to cool, or operate the vehicle until the appropriate transmission fluid temperature is reached.

Cold Check Procedure Use this procedure only as a reference to determine if the transmission has enough fluid to be operated safely until a hot check procedure can be made. The hot check procedure is the most accurate method to check the fluid level. Perform the hot check procedure at the first opportunity. Use this cold check procedure to check fluid level when the transmission temperature is between 27°C and 32°C (80°F and 90°F).

1. Locate the transmission

dipstick at the rear of the engine compartment, on the passenger side of the vehicle. See Engine Compartment Overview on page 10‑6 for more information.

2. Flip the handle up, then pull out

3.

the dipstick and wipe it with a clean rag or paper towel. Install the dipstick by pushing it back in all the way; wait three seconds, and then pull it back out again.

4. Check both sides of the dipstick and read the lower level. Repeat the check procedure to verify the reading.

5.

If the fluid level is below the COLD check band, add only enough fluid as necessary to bring the level into the COLD band. It does not take much fluid, generally less than 0.5 Liter (1 Pint). Do not overfill. 6. Perform a hot check at

7.

the first opportunity after the transmission reaches a normal operating temperature between 71°C to 93°C (160°F to 200°F). If the fluid level is in the acceptable range, push the dipstick back in all the way, then flip the handle down to lock the dipstick in place.

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10-16

Vehicle Care

Hot Check Procedure Use this procedure to check the transmission fluid level when the transmission fluid temperature is between 71°C and 93°C (160°F and 200°F). The hot check is the most accurate method to check the fluid level. The hot check should be performed at the first opportunity in order to verify the cold check. The fluid level rises as fluid temperature increases, so it is important to ensure the transmission temperature is within range.

See Engine Compartment Overview on page 10‑6 for more information.

2. Flip the handle up, then pull out

3.

the dipstick and wipe it with a clean rag or paper towel. Install the dipstick by pushing it back in all the way; wait three seconds, and then pull it back out again.

4. Check both sides of the dipstick and read the lower level. Repeat the check procedure to verify the reading.

6.

within the HOT band, and the transmission temperature is between 71°C and 93°C (160°F and 200°F), add or drain fluid as necessary to bring the level into the HOT band. If the fluid level is low, add only enough fluid to bring the level into the HOT band. It does not take much fluid, generally less than 0.5 L (1 pint). Do not overfill. If the fluid level is in the acceptable range, push the dipstick back in all the way, then flip the handle down to lock the dipstick in place.

1. Locate the transmission dipstick

5. Safe operating level is within the

at the rear of the engine compartment, on the passenger side of the vehicle.

HOT cross hatch band on the dipstick. If the fluid level is not

Consistency of Readings Always check the fluid level at least twice using the procedure described previously. Consistency (repeatable readings) is important to maintaining proper fluid level. If readings are still inconsistent, contact the dealer.

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How to Inspect the Engine Air Cleaner/Filter To inspect the air cleaner/filter, remove the engine air cleaner/filter from the vehicle by following Steps 1 through 6. When the engine air cleaner/filter is removed, lightly shake it to release loose dust and dirt. If the engine air cleaner/ filter remains covered with dirt, a new filter is required. Never use compressed air to clean the filter.

Engine Air Cleaner/Filter If the vehicle has a diesel engine, see “Pickup Models” under “Engine Air Cleaner/Filter” in the Duramax® Diesel Supplement for the correct inspection and replacement procedures. See Engine Compartment Overview on page 10‑6 for the location of the engine air cleaner/filter. When to Inspect the Engine Air Cleaner/Filter Inspect the air cleaner/filter at the scheduled maintenance intervals and replace it at the first oil change after each 80 000 km (50,000 mi) interval. See Maintenance Schedule on page 11‑3 for more information. If driving on dusty/dirty conditions, inspect the filter at each engine oil change.

Vehicle Care

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Replacing the Engine Air Cleaner/ Filter

1. Locate the air cleaner/filter

assembly. See Engine Compartment Overview on page 10‑6.

2. Loosen the four screws on the cover of the housing and lift up the cover.

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Vehicle Care

3. Remove the engine air cleaner/

filter from the housing. Take care to dislodge as little dirt as possible.

4. Clean the engine air cleaner/ filter sealing surfaces and the housing. Inspect or replace the engine air cleaner/filter.

5.

6. Reinstall the cover and tighten

the screws.

{ WARNING

Operating the engine with the air cleaner/filter off can cause you or others to be burned. The air cleaner not only cleans the air; it helps to stop flames if the engine backfires. Use caution when working on the engine and do not drive with the air cleaner/filter off.

Cooling System If the vehicle has the Duramax® Diesel engine, see the Duramax® Diesel Supplement for more information. The cooling system allows the engine to maintain the correct working temperature.

5.3 L Engine Shown (4.3 L, 4.8 L, 6.0 L and, 6.2 L Engines Similar)

A. Coolant Surge Tank B. Coolant Surge Tank

Pressure Cap

C. Engine Cooling Fan

(Out of View)

{ WARNING

An electric engine cooling fan can start even when the engine is not running. To avoid injury, always keep hands, clothing, and tools away from any engine cooling fan.

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{ WARNING

Heater and radiator hoses, and other engine parts, can be very hot. Do not touch them. If you do, you can be burned. Do not run the engine if there is a leak. If you run the engine, it could lose all coolant. That could cause an engine fire, and you could be burned. Get any leak fixed before you drive the vehicle.

Notice: Using coolant other than DEX-COOL® can cause premature engine, heater core, or radiator corrosion. In addition, the engine coolant could require changing sooner, at 50 000 km (30,000 mi) or 24 months, whichever occurs first. Any repairs would not be covered by the vehicle warranty. Always use DEX-COOL (silicate-free) coolant in the vehicle.

Engine Coolant The cooling system in the vehicle is filled with DEX-COOL® engine coolant. This coolant is designed to remain in the vehicle for 5 years or 240 000 km (150,000 mi), whichever occurs first. The following explains the cooling system and how to check and add coolant when it is low. If there is a problem with engine overheating, see Engine Overheating on page 10‑22. What to Use

{ WARNING

Adding only plain water or some other liquid to the cooling system can be dangerous. Plain water and other liquids, can boil before the proper coolant mixture will. The coolant warning system is set for the proper coolant mixture. With plain water or the wrong

(Continued)

Vehicle Care

10-19

WARNING (Continued)

mixture, the engine could get too hot but you would not get the overheat warning. The engine could catch fire and you or others could be burned. Use a 50/50 mixture of clean, drinkable water and DEX-COOL coolant.

Use a 50/50 mixture of clean, drinkable water and DEX-COOL coolant. If using this mixture, nothing else needs to be added. This mixture: . Gives freezing protection down

to −37°C (−34°F), outside temperature

. Gives boiling protection up to

129°C (265°F), engine temperature

. Protects against rust and

corrosion

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Vehicle Care

. Will not damage aluminum parts . Helps keep the proper engine

temperature

Notice: If an improper coolant mixture is used, the engine could overheat and be badly damaged. The repair cost would not be covered by the vehicle warranty. Too much water in the mixture can freeze and crack the engine, radiator, heater core, and other parts. Notice: If extra inhibitors and/or additives are used in the vehicle cooling system, the vehicle could be damaged. Use only the proper mixture of the engine coolant listed in this manual for the cooling system. See Recommended Fluids and Lubricants on page 11‑12 for more information.

Never dispose of engine coolant by putting it in the trash, pouring it on the ground, or into sewers, streams, or bodies of water. Have the coolant changed by an authorized service center, familiar with legal requirements regarding used coolant disposal. This will help protect the environment and your health. Checking Coolant The coolant surge tank is located in the engine compartment on the passenger side of the vehicle. See Engine Compartment Overview on page 10‑6 for more information on location. The vehicle must be on a level surface when checking the coolant level. Check to see if coolant is visible in the coolant surge tank. If the coolant inside the coolant surge tank is boiling, do not do anything else until

it cools down. If coolant is visible but the coolant level is not at or above the FULL COLD mark, add a 50/50 mixture of clean, drinkable water and DEX-COOL coolant at the coolant surge tank, but be sure the cooling system is cool before this is done.

The coolant level should be at or above the FULL COLD mark. If it is not, there may be a leak in the cooling system.

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How to Add Coolant to the Coolant Surge Tank for Gasoline Engines If the vehicle has a diesel engine, see “Cooling System” in the Duramax Diesel Supplement for the proper coolant fill procedure.

{ WARNING

You can be burned if you spill coolant on hot engine parts. Coolant contains ethylene glycol and it will burn if the engine parts are hot enough. Do not spill coolant on a hot engine.

Notice: This vehicle has a specific coolant fill procedure. Failure to follow this procedure could cause the engine to overheat and be severely damaged.

Vehicle Care

10-21

{ WARNING

If no coolant is visible in the surge tank, add coolant as follows:

An electric engine cooling fan under the hood can start up even when the engine is not running and can cause injury. Keep hands, clothing, and tools away from any underhood electric fan.

{ WARNING

Steam and scalding liquids from a hot cooling system can blow out and burn you badly. They are under pressure, and if you turn the coolant surge tank pressure cap — even a little — they can come out at high speed. Never turn the cap when the cooling system, including the coolant surge tank pressure cap, is hot. Wait for the cooling system and coolant surge tank pressure cap to cool if you ever have to turn the pressure cap.

1. Remove the coolant surge tank pressure cap when the cooling system, including the coolant surge tank pressure cap and upper radiator hose, is no longer hot. Turn the pressure cap slowly counterclockwise about one full turn. If a hiss is heard, wait for that to stop. A hiss means there is still some pressure left.

2. Keep turning the pressure cap

slowly, and remove it.

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Vehicle Care

mixture to the coolant surge tank until the level reaches the FULL COLD mark.

5. Replace the pressure cap. Be

sure the pressure cap is hand-tight and fully seated. 6. Verify coolant level after the

engine is shut off and the coolant is cold. If necessary, repeat coolant fill procedure Steps 1 through 6.

Notice: If the pressure cap is not tightly installed, coolant loss and possible engine damage may occur. Be sure the cap is properly and tightly secured.

Engine Overheating If the vehicle has the Duramax® Diesel engine, see the Duramax Diesel Supplement for more information. The vehicle has several indicators to warn of engine overheating.

There is a coolant temperature gauge on the vehicle's instrument panel. See Engine Coolant Temperature Gauge on page 5‑16. In addition, there are ENGINE OVERHEATED STOP ENGINE, ENGINE OVERHEATED IDLE ENGINE, and ENGINE POWER IS REDUCED messages in the Driver Information Center (DIC) on the instrument panel. See Engine Cooling System Messages on page 5‑41 and Engine Power Messages on page 5‑42. If the decision is made not to lift the hood when this warning appears, get service help right away. See Roadside Assistance Program (U.S. and Canada) on page 13‑7 or Roadside Assistance Program (Mexico) on page 13‑9. If the decision is made to lift the hood, make sure the vehicle is parked on a level surface.

3. Fill the coolant surge tank with the proper mixture to the FULL COLD mark.

4. With the coolant surge tank

pressure cap off, start the engine and let it run until the engine coolant temperature gauge indicates approximately 90°C (195°F). By this time, the coolant level inside the coolant surge tank may be lower. If the level is lower, add more of the proper

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Then check to see if the engine cooling fans are running. If the engine is overheating, both fans should be running. If they are not, do not continue to run the engine and have the vehicle serviced. Notice: Engine damage from running your engine without coolant is not covered by the vehicle warranty. See Overheated Engine Protection Operating Mode for information on driving to a safe place in an emergency. Notice: If the engine catches fire while driving with no coolant, the vehicle can be badly damaged. The costly repairs would not be covered by the vehicle warranty. See Overheated Engine Protection Operating Mode on page 10‑24 for information on driving to a safe place in an emergency.

If Steam is Coming from the Engine Compartment { WARNING

Steam from an overheated engine can burn you badly, even if you just open the hood. Stay away from the engine if you see or hear steam coming from it. Turn it off and get everyone away from the vehicle until it cools down. Wait until there is no sign of steam or coolant before you open the hood. If you keep driving when the vehicles engine is overheated, the liquids in it can catch fire. You or others could be badly burned. Stop the engine if it overheats, and get out of the vehicle until the engine is cool.

(Continued)

Vehicle Care

10-23

WARNING (Continued)

See Overheated Engine Protection Operating Mode on page 10‑24 for information on driving to a safe place in an emergency.

If No Steam is Coming from the Engine Compartment The ENGINE OVERHEATED STOP ENGINE or the ENGINE OVERHEATED IDLE ENGINE message, along with a low coolant condition, can indicate a serious problem. If there is an engine overheat warning, but no steam is seen or heard, the problem may not be too serious. Sometimes the engine can get a little too hot when the vehicle: . Climbs a long hill on a hot day . Stops after high-speed driving

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Vehicle Care

Idles for long periods in traffic Tows a trailer; see Trailer Towing on page 9‑78.

If the ENGINE OVERHEATED STOP ENGINE or the ENGINE OVERHEATED IDLE ENGINE message appears with no sign of steam, try this for a minute or so: 1. Turn the air conditioning off. 2. Turn the heater on to the highest

3.

temperature and to the highest fan speed. Open the windows as necessary. If stopped in a traffic jam, apply the brake, shift to N (Neutral); otherwise, shift to the highest gear while driving — D (Drive) or 3 (Third).

If the temperature overheat gauge is no longer in the overheat zone or an overheat warning no longer displays, the vehicle can be driven. Continue to drive the vehicle slowly for about 10 minutes. Keep a safe

vehicle distance from the vehicle in front. If the warning does not come back on, continue to drive normally. If the warning continues, pull over, stop, and park the vehicle right away. If there is no sign of steam, idle the engine for five minutes while parked. If the warning is still displayed, turn off the engine until it cools down. Also, see “Overheated Engine Protection Operating Mode” later in this section.

Overheated Engine Protection Operating Mode If an overheated engine condition exists and the ENGINE POWER IS REDUCED message displays, an overheat protection mode which alternates firing groups of cylinders helps to prevent engine damage. In this mode, a loss in power and engine performance will be noticed.