2012 GMC Sierra Owners Manual

This operating mode allows the vehicle to be driven to a safe place in an emergency. Driving extended km (mi) and/or towing a trailer in the overheat protection mode should be avoided. Notice: After driving in the overheated engine protection operating mode, to avoid engine damage, allow the engine to cool before attempting any repair. The engine oil will be severely degraded. Repair the cause of coolant loss, change the oil and reset the oil life system. See Engine Oil on page 10‑7.

Engine Fan If the vehicle has a clutched engine cooling fan, when the clutch is engaged, the fan spins faster to provide more air to cool the engine. In most everyday driving conditions, the fan is spinning slower and the clutch is not fully engaged. This improves fuel economy and reduces fan noise. Under heavy vehicle

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loading, trailer towing, and/or high outside temperatures, the fan speed increases as the clutch more fully engages, so an increase in fan noise may be heard. This is normal and should not be mistaken as the transmission slipping or making extra shifts. It is merely the cooling system functioning properly. The fan will slow down when additional cooling is not required and the clutch disengages. This fan noise may also be heard when starting the engine. It will go away as the fan clutch partially disengages. If the vehicle has electric cooling fans, the fans may be heard spinning at low speed during most everyday driving. The fans may turn off if no cooling is required. Under heavy vehicle loading, trailer towing, high outside temperatures, or operation of the air conditioning system, the fans may change to high speed and an increase in fan noise may be heard. This is normal and indicates that the cooling

system is functioning properly. The fans will change to low speed when additional cooling is no longer required.

Power Steering Fluid

See Engine Compartment Overview on page 10‑6 for reservoir location. When to Check Power Steering Fluid It is not necessary to regularly check power steering fluid unless there is a leak suspected in the system or an unusual noise is heard. A fluid loss in this system could indicate a problem. Have the system inspected and repaired.

Vehicle Care

10-25

How to Check Power Steering Fluid Notice: Extremely small amounts of contamination can cause steering system damage and cause it to not work properly. Do not allow contaminants to contact the fluid side of the reservoir cap/ dipstick or to enter the reservoir. To check the power steering fluid: 1. Turn the key off and let the

engine compartment cool down. 2. Wipe the cap and the top of the

reservoir clean.

3. Unscrew the cap and wipe the

dipstick with a clean rag.

4. Replace the cap and completely

tighten it.

5. Remove the cap again and look at the fluid level on the dipstick.

The level should be at the FULL COLD mark. If necessary, add only enough fluid to bring the level up to the mark.

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10-26

Vehicle Care

What to Use To determine what kind of fluid to use, see Recommended Fluids and Lubricants on page 11‑12. Always use the proper fluid. Notice: Use of the incorrect fluid may damage the vehicle and the damages may not be covered by the vehicle's warranty. Always use the correct fluid listed in Recommended Fluids and Lubricants on page 11‑12.

Washer Fluid

What to Use When windshield washer fluid needs to be added, be sure to read the manufacturer's instructions before use. Use a fluid that has sufficient protection against freezing in an area where the temperature may fall below freezing.

Adding Washer Fluid The vehicle has a low washer fluid message on the DIC that comes on when the washer fluid is low. The message is displayed for 15 seconds at the start of each ignition cycle. When the WASHER FLUID LOW ADD FLUID message displays, washer fluid will need to be added to the windshield washer fluid reservoir.

Open the cap with the washer symbol on it. Add washer fluid until the tank is full. See Engine Compartment Overview on page 10‑6 for reservoir location.

Notice

. When using concentrated

washer fluid, follow the manufacturer's instructions for adding water.

. Do not mix water with

ready-to-use washer fluid. Water can cause the solution to freeze and damage the washer fluid tank and other parts of the washer system.

. Fill the washer fluid tank only

three-quarters full when it is very cold. This allows for fluid expansion if freezing occurs, which could damage the tank if it is completely full.

. Do not use engine coolant

(antifreeze) in the windshield washer. It can damage the windshield washer system and paint.

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Brakes This vehicle has front disc brakes and could have rear drum brakes or rear disc brakes. Disc brake pads have built-in wear indicators that make a high-pitched warning sound when the brake pads are worn and new pads are needed. The sound can come and go or be heard all the time the vehicle is moving, except when applying the brake pedal firmly.

{ WARNING

The brake wear warning sound means that soon the brakes will not work well. That could lead to a crash. When the brake wear warning sound is heard, have the vehicle serviced.

Notice: Continuing to drive with worn-out brake pads could result in costly brake repair.

Some driving conditions or climates can cause a brake squeal when the brakes are first applied or lightly applied. This does not mean something is wrong with the brakes. Properly torqued wheel nuts are necessary to help prevent brake pulsation. When tires are rotated, inspect brake pads for wear and evenly tighten wheel nuts in the proper sequence to torque specifications in Capacities and Specifications on page 12‑2. If the vehicle has rear drum brakes, they do not have wear indicators, but if a rear brake rubbing noise is heard, have the rear brake linings inspected immediately. Rear brake drums should be removed and inspected each time the tires are removed for rotation or changing. Drum brakes have an inspection hole to inspect lining wear during scheduled maintenance. When the front brake pads are replaced, have the rear brakes inspected, too.

Vehicle Care

10-27

Brake linings should always be replaced as complete axle sets. Brake Pedal Travel See your dealer if the brake pedal does not return to normal height, or if there is a rapid increase in pedal travel. This could be a sign that brake service might be required. Brake Adjustment Every time the brakes are applied, with or without the vehicle moving, the brakes adjust for wear. Replacing Brake System Parts The braking system on a vehicle is complex. Its many parts have to be of top quality and work well together if the vehicle is to have really good braking. The vehicle was designed and tested with top-quality brake parts. When parts of the braking system are replaced, be sure to get new, approved replacement parts.

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10-28

Vehicle Care

If this is not done, the brakes might not work properly. For example, installing disc brake pads that are wrong for the vehicle, can change the balance between the front and rear brakes — for the worse. The braking performance expected can change in many other ways if the wrong replacement brake parts are installed.

Brake Fluid

The brake master cylinder reservoir is filled with DOT 3 brake fluid. See Engine Compartment Overview on page 10‑6 for the location of the reservoir.

There are only two reasons why the brake fluid level in the reservoir might go down:

The brake fluid level goes down because of normal brake lining wear. When new linings are installed, the fluid level goes back up.

. A fluid leak in the brake

hydraulic system can also cause a low fluid level. Have the brake hydraulic system fixed, since a leak means that sooner or later the brakes will not work well.

Do not top off the brake fluid. Adding fluid does not correct a leak. If fluid is added when the linings are worn, there will be too much fluid when new brake linings are installed. Add or remove brake fluid, as necessary, only when work is done on the brake hydraulic system.

{ WARNING

If too much brake fluid is added, it can spill on the engine and burn, if the engine is hot enough. You or others could be burned, and the vehicle could be damaged. Add brake fluid only when work is done on the brake hydraulic system. See “Checking Brake Fluid” in this section.

When the brake fluid falls to a low level, the brake warning light comes on. See Brake System Warning Light on page 5‑25. Refer to the Maintenance Schedule to determine when to check the brake fluid. See Maintenance Schedule on page 11‑3.

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Checking Brake Fluid Check brake fluid by looking at the brake fluid reservoir. See Engine Compartment Overview on page 10‑6.

The fluid level should be above MIN. If it is not, have the brake hydraulic system checked to see if there is a leak.

Vehicle Care

10-29

Notice

. Using the wrong fluid

can badly damage brake hydraulic system parts. For example, just a few drops of mineral-based oil, such as engine oil, in the brake hydraulic system can damage brake hydraulic system parts so badly that they will have to be replaced. Do not let someone put in the wrong kind of fluid.

. If brake fluid is spilled on the

vehicle's painted surfaces, the paint finish can be damaged. Be careful not to spill brake fluid on the vehicle. If you do, wash it off immediately.

After work is done on the brake hydraulic system, make sure the level is above the MIN but not over the MAX mark.

What to Add Use only new DOT 3 brake fluid from a sealed container. See Recommended Fluids and Lubricants on page 11‑12. Always clean the brake fluid reservoir cap and the area around the cap before removing it. This helps keep dirt from entering the reservoir.

{ WARNING

With the wrong kind of fluid in the brake hydraulic system, the brakes might not work well. This could cause a crash. Always use the proper brake fluid.

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10-30

Vehicle Care

Battery If the vehicle is a Hybrid, see the Hybrid Supplement for more information. This vehicle has a maintenance free battery (or batteries). Refer to the replacement number on the original battery label when a new battery is needed. See Engine Compartment Overview on page 10‑6 for battery location.

{ WARNING

Battery posts, terminals, and related accessories contain lead and lead compounds, chemicals known to the State of California to cause cancer and reproductive harm. Wash hands after handling.

Vehicle Storage

{ WARNING

Batteries have acid that can burn you and gas that can explode. You can be badly hurt if you are not careful. See Jump Starting on page 10‑88 for tips on working around a battery without getting hurt.

Infrequent Usage: Remove the black, negative (−) cable from the battery to keep the battery from running down. Extended Storage: Remove the black, negative (−) cable from the battery or use a battery trickle charger.

Four-Wheel Drive

Transfer Case

When to Check Lubricant Refer to Maintenance Schedule on page 11‑3 to determine when to check the lubricant.

How to Check Lubricant

Electric Shift Transfer Case

A. Fill Plug B. Drain Plug

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Vehicle Care

10-31

When to Change Lubricant Refer to Maintenance Schedule on page 11‑3 to determine how often to change the lubricant.

What to Use Refer to Recommended Fluids and Lubricants on page 11‑12 to determine what kind of lubricant to use.

Front Axle

When to Check and Change Lubricant It is not necessary to regularly check front axle fluid unless a leak is suspected, or an unusual noise is heard. A fluid loss could indicate a problem. Have it inspected and repaired.

Manual Shift Transfer Case

Active Transfer Case

A. Fill Plug B. Drain Plug

A. Fill Plug B. Drain Plug To get an accurate reading, the vehicle should be on a level surface. If the level is below the bottom of the fill plug hole, located on the transfer case, some lubricant will need to be added. Add enough lubricant to raise the level to the bottom of the fill plug hole. Use care not to overtighten the plug.

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10-32

Vehicle Care

How to Check Lubricant To get an accurate reading, the vehicle should be on a level surface.

1500 Series

A. Fill Plug B. Drain Plug

What to Use Refer to Recommended Fluids and Lubricants on page 11‑12 to determine what kind of lubricant to use.

Rear Axle

When to Check Lubricant It is not necessary to regularly check rear axle fluid unless a leak is suspected or an unusual noise is heard. A fluid loss could indicate a problem. Have it inspected and repaired. All axle assemblies are filled by volume of fluid during production. They are not filled to reach a certain level. When checking the fluid level on any axle, variations in the readings can be caused by factory fill differences between the minimum and the maximum fluid volume.

All Except 1500 Series

A. Fill Plug B. Drain Plug . When the differential is cold, add

enough lubricant to raise the level from 0 mm (0 in) to 3.2 mm (1/8 in) below the fill plug hole.

. When the differential is at

operating temperature (warm), add enough lubricant to raise the level to the bottom of the fill plug hole.

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Also, if a vehicle has just been driven before checking the fluid level, it may appear lower than normal because fluid has traveled out along the axle tubes and has not drained back to the sump area. Therefore, a reading taken five minutes after the vehicle has been driven will appear to have a lower fluid level than a vehicle that has been stationary for an hour or two. Remember that the rear axle assembly must be supported to get a true reading.

How to Check Lubricant

2500HD with 6.0 L

All Other Series and Engines

Vehicle Care

10-33

To get an accurate reading, the vehicle should be on a level surface.

For all 4.3 L, 4.8 L and 5.3 L 1500 Series applications, the proper level is 1.0 mm to 19.0 mm (0.04 in to 0.7 in) below the bottom of the fill hole, located on the rear axle. Add only enough fluid to reach the proper level. For all 6.0 L and 6.2 L 1500 Series applications, the proper level is from 15 mm to 40 mm (0.6 in to 1.6 in) below the bottom of the fill plug hole, located on the rear axle. Add only enough fluid to reach the proper level. For all 6.0 L 2500HD Series applications, the proper level is from 0 mm to 13 mm (0 to 0.5 in) below the bottom of the fill plug hole, located on the rear axle. Add only enough fluid to reach the proper level.

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10-34

Vehicle Care

For all 6.6 L Duramax Diesel 2500HD Series applications and all 3500 Series applications, the proper level is from 17 mm to 21 mm (0.6 in to 0.8 in) below the bottom of the fill plug hole, located on the rear axle. Add only enough fluid to reach the proper level.

What to Use Refer to Recommended Fluids and Lubricants on page 11‑12 to determine what kind of lubricant to use.

Noise Control System The following information relates to compliance with federal noise emission standards for vehicles with a Gross Vehicle Weight Rating (GVWR) of more than 4 536 kg (10,000 lbs). The noise control system warranty is given in your warranty booklet. These standards apply only to vehicles sold in the United States.

Federal law prohibits the following acts or the causing thereof: 1. The removal or rendering inoperative by any person, other than for purposes of maintenance, repair or replacement, of any device or element of design incorporated into any new vehicle for the purpose of noise control, prior to its sale or delivery to the ultimate purchaser or while it is in use; or 2. The use of the vehicle after such device or element of design has been removed or rendered inoperative by any person. Among those acts presumed to constitute tampering are the acts listed below.

Insulation: Removal of the noise shields or any underhood insulation.

Engine: Removal or rendering engine speed governor, if the vehicle has one, inoperative so as to allow engine speed to exceed manufacturer specifications.

Fan and Drive: . Removal of fan clutch, if the

vehicle has one, or rendering clutch inoperative.

. Removal of the fan shroud, if the

vehicle has one.

Air Intake: . Removal of the air cleaner

silencer.

. Modification of the air cleaner.

Exhaust: . Removal of the muffler and/or

resonator.

. Removal of the exhaust pipes

and exhaust pipe clamps.

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Starter Switch Check

{ WARNING When you are doing this inspection, the vehicle could move suddenly. If the vehicle moves, you or others could be injured.

1. Before starting this check, be

sure there is enough room around the vehicle.

2. Firmly apply both the parking brake and the regular brake. See Parking Brake on page 9‑54. Do not use the accelerator pedal, and be ready to turn off the engine immediately if it starts.

3. Try to start the engine in each gear. The vehicle should start only in P (Park) or N (Neutral).

If the vehicle starts in any other position, contact your dealer for service.

Automatic Transmission Shift Lock Control Function Check

{ WARNING When you are doing this inspection, the vehicle could move suddenly. If the vehicle moves, you or others could be injured.

1. Before starting this check, be

sure there is enough room around the vehicle. It should be parked on a level surface.

2. Firmly apply the parking

brake. See Parking Brake on page 9‑54. Be ready to apply the regular brake immediately if the vehicle begins to move.

Vehicle Care

10-35

3. With the engine off, turn the

ignition on, but do not start the engine. Without applying the regular brake, try to move the shift lever out of P (Park) with normal effort. If the shift lever moves out of P (Park), contact your dealer for service.

Ignition Transmission Lock Check While parked, and with the parking brake set, try to turn the ignition to LOCK/OFF in each shift lever position.

The ignition should turn to LOCK/OFF only when the shift lever is in P (Park). The ignition key should come out only in LOCK/OFF.

Contact your dealer if service is required.

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10-36

Vehicle Care

Park Brake and P (Park) Mechanism Check { WARNING

When you are doing this check, the vehicle could begin to move. You or others could be injured and property could be damaged. Make sure there is room in front of the vehicle in case it begins to roll. Be ready to apply the regular brake at once should the vehicle begin to move.

Park on a fairly steep hill, with the vehicle facing downhill. Keeping your foot on the regular brake, set the parking brake.

To check the parking brake's holding ability: With the engine running and the transmission in N (Neutral), slowly remove foot pressure from the regular brake pedal. Do this until the vehicle is held by the parking brake only. To check the P (Park) mechanism's holding ability: With the engine running, shift to P (Park). Then release the parking brake followed by the regular brake.

Contact your dealer if service is required.

Wiper Blade Replacement Windshield wiper blades should be inspected for wear or cracking. See Maintenance Schedule on page 11‑3 for more information on wiper blade inspection. Replacement blades come in different types and are removed in different ways. To remove the wiper blade: 1. Pull the windshield wiper arm

connector away from the windshield.

2. Squeeze the grooved areas on each side of the blade, and turn the blade assembly away from the arm connector.

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Headlamp Aiming The vehicle has a visual optical headlamp aiming system. The aim of the headlamps has been preset at the factory and should need no further adjustment. However, if the vehicle is damaged in a crash, the aim of the headlamps may be affected and adjustment may be necessary. If oncoming vehicles flash their high beams at you, this may mean the vertical aim of the headlamps needs to be adjusted. It is recommended that the vehicle be taken to the dealer for service if the headlamps need to be adjusted. It is possible, however, to re-aim the headlamps as described.

Vehicle Care

10-37

The vehicle should: . Be placed so the headlamps

are 7.6 m (25 ft) from a light‐colored wall.

. Have all four tires on a level

surface which is level all the way to the wall.

. Be placed so it is perpendicular

to the wall.

. Not have any snow, ice, or mud

on it.

. Be fully assembled and all other

work stopped while headlamp aiming is being performed. . Be loaded with a full tank of fuel and one person or 75 kg (160 lbs) sitting on the driver seat.

. Have the tires properly inflated. . Have the spare tire in its proper

location in the vehicle.

3.

Install the new blade onto the arm connector and make sure the grooved areas are fully set in the locked position.

For the proper type and size, see Maintenance Replacement Parts on page 11‑15.

Glass Replacement If the windshield or front side glass must be replaced, see your dealer to determine the correct replacement glass.

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10-38

Vehicle Care

Headlamp aiming is done with the vehicle's low-beam headlamps. The high-beam headlamps will be correctly aimed if the low-beam headlamps are aimed properly. To adjust the vertical aim: 1. Open the hood. See Hood on

page 10‑5

2. Locate the aim dot on the lens of

the low‐beam headlamp.

3. Record the distance from the ground to the aim dot on the low‐beam headlamp.

4. At a wall, measure from the

ground upward (A) to the recorded distance from Step 3 and mark it.

5. Draw or tape a horizontal line (B)

on the wall the width of the vehicle at the height of the mark in Step 4.

Notice: Do not cover a headlamp to improve beam cut-off when aiming. Covering a headlamp may cause excessive heat build-up which may cause damage to the headlamp.

6. Turn on the low-beam

headlamps and place a piece of cardboard or equivalent in front of the headlamp not being adjusted. This allows only the beam of light from the headlamp being adjusted to be seen on the flat surface.

7. Locate the vertical headlamp

aiming screws, which are under the hood near each headlamp assembly. The adjustment screw can be turned with an E8 Torx® socket.

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Bulb Replacement For the proper type of replacement bulbs, see Replacement Bulbs on page 10‑43. For any bulb‐changing procedure not listed in this section, contact your dealer.

Halogen Bulbs

{ WARNING

Halogen bulbs have pressurized gas inside and can burst if you drop or scratch the bulb. You or others could be injured. Be sure to read and follow the instructions on the bulb package.

8. Turn the vertical aiming screw

until the headlamp beam is aimed to the horizontal tape line. Turn it clockwise or counterclockwise to raise or lower the angle of the beam.

9. Make sure that the light from the

headlamp is positioned at the bottom edge of the horizontal tape line. The lamp on the left (A) shows the correct headlamp aim. The lamp on the right (B) shows the incorrect headlamp aim.

10. Repeat Steps 7 through 9 for

the opposite headlamp.

Vehicle Care

10-39

Headlamps, Front Turn Signal, Sidemarker, and Parking Lamps

A. Side Marker Lamp B. Low-Beam Headlamp C. High-Beam Headlamp D. Park/Turn Signal Lamp 1. Open the hood. See Hood on

page 10‑5

2. When replacing a driver side

bulb on a vehicle with duel batteries, see your dealer.

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10-40

Vehicle Care

3. When replacing a bulb on the

passenger side, remove the Engine Air Cleaner cover. See Engine Air Cleaner/Filter on page 10‑17 for more information.

4. Reach in and access the bulb sockets from inside the engine compartment.

5. Turn the bulb socket

counterclockwise to remove it from the headlamp assembly and pull it straight out.

6. Unplug the electrical connector

from the old bulb by releasing the clips on the bulb socket. 7. Replace it with a new bulb. 8. Plug in the electrical connector. 9. Reinstall the new bulb socket

into the headlamp assembly and turn it clockwise to secure.

Pick-Up Box Identification and Fender Marker Lamps The pick-up box identification lamps are LEDs. For replacement of the LED lighting assembly contact your dealer. To replace a pickup box fender marker lamp bulb: 1. Press the tab from the back to

remove the lamp.

2. Turn the bulb socket

counterclockwise to remove from the lamp assembly.

3. Gently pry the bulb from the

socket. Install the new bulb in socket.

4. 5. Reinstall socket into lamp

assembly.

6. Reinstall the lamp assembly.

Taillamps (Chassis Cab Models)

A. Backup Lamp B. Stoplamp/Taillamp/Turn

Signal Lamp

To replace one of these bulbs: 1. Remove the four screws. 2. Lift the lens off the lamp

assembly.

3. Turn the old bulb

counterclockwise and pull the it straight out from the socket.

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To replace one of these bulbs: 1. Open the tailgate. See Tailgate

on page 2‑10 for more information.

4.

Install a new bulb into the socket, turn it clockwise, and press it in until it is tight.

5. Reinstall the lens and the four

screws.

Taillamps, Turn Signal, Stoplamps, and Back-Up Lamps

Vehicle Care

10-41

3. Turn the bulb socket

counterclockwise to remove it from the taillamp assembly. 4. Pull the old bulb straight out

from the socket.

5. Press a new bulb into the socket and turn the socket clockwise into the taillamp assembly.

6. Reinstall the taillamp

assembly.

2. Remove the two rear lamp assembly screws near the tailgate latch strikerpost and pull rearward until disengaging the two outer pins on the taillamp assembly from the vehicle.

A. Stoplamp/Taillamp/Turn

Signal Lamp

B. Back-up Lamp

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10-42

Vehicle Care

Center High-Mounted Stoplamp (CHMSL) and Cargo Lamp

A. Cargo Lamp B. Center High-Mounted Stoplamp

(CHMSL) Bulb

To replace one of these bulbs:

1. Remove the two screws and lift

off the lamp assembly.

2. On the reverse side of the lamp

assembly, remove the bulb socket by turning it one quarter turn counterclockwise and pull it straight out.

3. Remove the bulb by pulling it

4.

5.

straight out of the socket. Install the bulb by pushing the bulb straight into the socket. Install the bulb socket into the lamp assembly by turning it one quarter turn clockwise.

6. Reinstall the lamp assembly and

tighten the screws.

License Plate Lamp

A. License Plate Lamp Housing B. Bulb C. Bulb Socket To replace one of these bulbs: 1. Using a small flat-bladed tool,

insert the blade end at the back edge of the rear license plate lamp housing (A).

2. Gently push forward while lifting

the back edge of the lamp housing from the bumper opening.

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3. Turn the bulb socket (C)

one‐quarter turn to release the bulb socket from the lamp housing (A).

4. Pull the bulb (B) from the bulb

socket (C).

5. Reverse the steps to install.

Replacement Bulbs

Exterior Lamp

Back-up Lamp Back-up Lamp* Cargo Lamp and Center High-Mounted Stoplamp (CHMSL) Fender Marker Front Turn Signal Lamp, Sidemarker Lamp, and Parking Lamp

Bulb

Number

921
1156

912

W5WLL

3157A

Exterior Lamp

Bulb

Number

High-Beam Headlamp Low-Beam Headlamp License Plate Lamp Stoplamp/Taillamp/ Turn Signal Lamp Sidemarker Lamp Stoplamp/Turn Signal Lamp/ Taillamp* * Chassis Cab Models

9005

H11

168

3047K

194

1157

For replacement bulbs not listed here, contact your dealer.

Vehicle Care

10-43

Electrical System

Electrical System Overload The vehicle has fuses and circuit breakers to protect against an electrical system overload. When the current electrical load is too heavy, the circuit breaker opens and closes, protecting the circuit until the current load returns to normal or the problem is fixed. This greatly reduces the chance of circuit overload and fire caused by electrical problems. Fuses and circuit breakers protect power devices in the vehicle. Replace a bad fuse with a new one of the identical size and rating. If there is a problem on the road and a fuse needs to be replaced, the same amperage fuse can be borrowed. Choose some feature of the vehicle that is not needed to use and replace it as soon as possible.

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10-44

Vehicle Care

Headlamp Wiring An electrical overload may cause the lamps to go on and off, or in some cases to remain off. Have the headlamp wiring checked right away if the lamps go on and off or remain off. Windshield Wipers If the wiper motor overheats due to heavy snow or ice, the windshield wipers will stop until the motor cools and will then restart. Although the circuit is protected from electrical overload, overload due to heavy snow or ice may cause wiper linkage damage. Always clear ice and heavy snow from the windshield before using the windshield wipers. If the overload is caused by an electrical problem and not snow or ice, be sure to get it fixed.

Fuses and Circuit Breakers If the vehicle is a hybrid, see the hybrid supplement for more information. The wiring circuits in the vehicle are protected from short circuits by a combination of fuses, circuit breakers and fusible thermal links. This greatly reduces the chance of fires caused by electrical problems. Look at the silver-colored band inside the fuse. If the band is broken or melted, replace the fuse. Be sure you replace a bad fuse with a new one of the identical size and rating.

If you ever have a problem on the road and don't have a spare fuse, you can borrow one that has the same amperage. Just pick some feature of your vehicle that you can get along without– like the radio or accessory power outlet– and use its fuse, if it is the correct amperage. Replace it as soon as you can.

Engine Compartment Fuse Block If the vehicle has a diesel engine, see the Duramax Diesel supplement for more information. If the vehicle is a hybrid, see the hybrid supplement for more information.

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Vehicle Care

10-45

The Engine Compartment Fuse Block is located in the engine compartment, on the driver side of the vehicle.

Lift the cover to access the fuse block. Notice: Spilling liquid on any electrical component on the vehicle may damage it. Always keep the covers on any electrical component. To remove fuses, hold the end of the fuse between your thumb and index finger and pull straight out.

Fuses

Usage

Fuses

Right Trailer Stop/ Turn Lamp Electronic Suspension Control, Automatic Level Control Exhaust Left Trailer Stop/ Turn Lamp

Usage Engine Controls Engine Control Module, Throttle Control Trailer Brake Controller Front Washer Oxygen Sensor

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Vehicle Care

Fuses

Usage

Fuses

Usage

10

11

12

13

14

15

16

17

18

19

20

21

Antilock Brakes System 2
Trailer Back-up Lamps Driver Side Low-Beam Headlamp Engine Control Module (Battery) Fuel Injectors, Ignition Coils (Right Side) Transmission Control Module (Battery) Vehicle Back-up Lamps Passenger Side Low-Beam Headlamp Air Conditioning Compressor Oxygen Sensors Transmission Controls (Ignition) Fuel Pump Fuel System Control Module

22
23

24

25
26

27

28
29

30

31

32

33
34

35

Not Used Not Used Fuel Injectors, Ignition Coils (Left Side) Trailer Park Lamps Driver Side Park Lamps Passenger Side Park Lamps Fog Lamps Horn Passenger Side High-Beam Headlamp Daytime Running Lamps (DRL) Driver Side High-Beam Headlamp Daytime Running Lamps 2
Sunroof Key Ignition System, Theft Deterrent System

Fuses

Usage 36 Windshield Wiper

37

38
39
40
41
42

43

44
45
46
47

48

49

50

SEO B2 Upfitter Usage (Battery) Electric Adjustable Pedals Climate Controls (Battery) Airbag System (Ignition) Amplifier Audio System Miscellaneous (Ignition), Cruise Control Not Used Airbag System (Battery) Instrument Panel Cluster Power Take-Off Auxiliary Climate Control (Ignition) Center High-Mounted Stoplamp (CHMSL) Rear Defogger

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Fuses

Usage

51

52

53
54
55

56

Heated Mirrors SEO B1 Upfitter Usage (Battery) Accessory Power Outlet SEO Upfitter Usage Climate Controls (Ignition) Engine Control Module, Secondary Fuel Pump (Ignition)

J-Case Fuses

Usage

57
58

59

60

61

Cooling Fan 1
Not Used Heavy Duty Antilock Brake System Cooling Fan 2
Antilock Brake System 1

Vehicle Care

10-47

Usage

Relays

Usage

Starter Stud 2 (Trailer Brakes) Left Bussed Electrical Center 1
Not Used Not Used Transfer Case Stud 1 (Trailer Connector Battery Power) (Optional - 40A Fuse Required) Mid-Bussed Electrical Center 1
Climate Control Blower Not Used Left Bussed Electrical Center 2

FAN HI

FAN LO

FAN CNTRL

HDLP LO/HID FOG LAMP A/C CMPRSR STRTR PWR/TRN FUEL PMP PRK LAMP REAR DEFOG RUN/CRNK

Cooling Fan High Speed Cooling Fan Low Speed Cooling Fan Control Low-Beam Headlamp Front Fog Lamps Air Conditioning Compressor Starter Powertrain Fuel Pump Parking Lamps

Rear Defogger

Switched Power

J-Case Fuses

62
63

64

65
66
67

68

69

70
71

72

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Vehicle Care

Instrument Panel Fuse Block

The instrument panel fuse block access door is located on the driver side edge of the instrument panel. Pull off the cover to access the fuse block.

The vehicle may not be equipped with all of the fuses, relays, and features shown.

Fuses

Usage

Rear Seats Rear Accessory Power Outlet

Fuses

Usage Steering Wheel Controls Backlight Driver Door Module Dome Lamps, Driver Side Turn Signal

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Fuses

Usage

Fuses

10

11

12

13
14

15

16

Driver Side Turn Signal, Stoplamp Instrument Panel Back Lighting Passenger Side Turn Signal, Stoplamp Passenger Door Module, Driver Unlock Power Door Lock 2
(Unlock Feature) Power Door Lock 2
(Lock Feature) Stoplamps, Center High‐Mounted Stoplamp Rear Climate Controls Power Mirror Body Control Module (BCM) Accessory Power Outlets

17

18

19

20

21

22

23
24

25

26

Usage Interior Lamps Power Door Lock 1
(Unlock Feature) Rear Seat Entertainment Ultrasonic Rear Parking Assist, Power Liftgate Power Door Lock 1
(Lock Feature) Driver Information Center (DIC) Rear Wiper Cooled Seats Driver Seat Module, Remote Keyless Entry System Driver Power Door Lock (Unlock Feature)

Vehicle Care

10-49

Circuit Breaker

LT DR

Usage

Driver Side Power Window Circuit Breaker

Harness Connector

LT DR

BODY BODY

Usage

Driver Door Harness Connection Harness Connector Harness Connector

Center Instrument Panel Fuse Block The center instrument panel fuse block is located underneath the instrument panel, to the left of the steering column.

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10-50

Vehicle Care

Top View

Harness Connector

BODY 2

BODY 1

BODY 3

HEADLINER 3

Usage

Body Harness Connector 2
Body Harness Connector 1
Body Harness Connector 3
Headliner Harness Connector 3

Harness Connector

HEADLINER 2

HEADLINER 1

SEO/

UPFITTER

Usage

Headliner Harness Connector 2
Headliner Harness Connector 1
Special Equipment Option Upfitter Harness Connector

Circuit Breaker

CB1

CB2

CB3

CB4

Usage

Passenger Side Power Window Circuit Breaker Passenger Seat Circuit Breaker Driver Seat Circuit Breaker Rear Sliding Window

Wheels and Tires

Tires Every new GM vehicle has high-quality tires made by a leading tire manufacturer. See the warranty manual for information regarding the tire warranty and where to get service. For additional information refer to the tire manufacturer.

{ WARNING . Poorly maintained and

improperly used tires are dangerous.

. Overloading the tires can

cause overheating as a result of too much flexing. There could be a blowout and a serious crash. See Vehicle Load Limits on page 9‑16.

(Continued)

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WARNING (Continued)

WARNING (Continued)

. Underinflated tires pose the same danger as overloaded tires. The resulting crash could cause serious injury. Check all tires frequently to maintain the recommended pressure. Tire pressure should be checked when the tires are cold.

. Overinflated tires are more likely to be cut, punctured, or broken by a sudden impact— such as when hitting a pothole. Keep tires at the recommended pressure.

. Worn or old tires can cause a

crash. If the tread is badly worn, replace them.

. Replace any tires that have been damaged by impacts with potholes, curbs, etc.

(Continued)

. Improperly repaired tires can

cause a crash. Only the dealer or an authorized tire service center should repair, replace, dismount, and mount the tires.

. Do not spin the tires in

excess of 56 km/h (35 mph) on slippery surfaces such as snow, mud, ice, etc. Excessive spinning may cause the tires to explode.

See Tire Pressure for High-Speed Operation on page 10‑60 for inflation pressure adjustment for high speed driving.

20‐Inch Tires If the vehicle has 20‐inch P275/55R20 size tires, they are classified as touring tires and are designed for on road use.

Vehicle Care

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The low‐profile, wide tread design is not recommended for “off‐road” driving or commercial uses such as snow plowing. See Off-Road Driving on page 9‑6 and Adding a Snow Plow or Similar Equipment on page 9‑106 for additional information. Notice: Low‐profile tires are more susceptible to damage from road hazards or curb impact than standard profile tires. Tire and/or wheel assembly damage can occur when coming into contact with road hazards like, potholes, or sharp edged objects, or when sliding into a curb. The warranty does not cover this type of damage. Keep tires set to the correct inflation pressure and, when possible, avoid contact with curbs, potholes, and other road hazards.

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Vehicle Care

Tire Sidewall Labeling Useful information about a tire is molded into the sidewall. The examples show a typical passenger and light truck tire sidewall.

Passenger (P‐Metric) Tire (A) Tire Size: The tire size code is a combination of letters and numbers used to define a particular tire's width, height, aspect ratio, construction type,

and service description. See the “Tire Size” illustration later in this section for more detail. (B) TPC Spec (Tire Performance Criteria Specification): Original equipment tires designed to GM's specific tire performance criteria have a TPC specification code molded onto the sidewall. GM's TPC specifications meet or exceed all federal safety guidelines. (C) DOT (Department of Transportation): The Department of Transportation (DOT) code indicates that the tire is in compliance with the U.S. Department of Transportation Motor Vehicle Safety Standards.

(D) Tire Identification Number (TIN): The letters and numbers following the DOT code are the Tire Identification Number (TIN). The TIN shows the manufacturer and plant code, tire size, and date the tire was manufactured. The TIN is molded onto both sides of the tire, although only one side may have the date of manufacture. (E) Tire Ply Material: The type of cord and number of plies in the sidewall and under the tread. (F) Uniform Tire Quality Grading (UTQG): Tire manufacturers are required to grade tires based on three performance factors: treadwear, traction, and temperature resistance. For more information, see Uniform Tire Quality Grading on page 10‑70.

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(G) Maximum Cold Inflation Load Limit: Maximum load that can be carried and the maximum pressure needed to support that load. For information on recommended tire pressure see Tire Pressure on page 10‑58 and Vehicle Load Limits on page 9‑16.

Light Truck (LT-Metric) Tire

(A) Tire Size: The tire size code is a combination of letters and numbers used to define a particular tire's width, height,

Vehicle Care

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(D) DOT (Department of Transportation): The Department of Transportation (DOT) code indicates that the tire is in compliance with the U.S. Department of Transportation Motor Vehicle Safety Standards. (E) Tire Identification Number (TIN): The letters and numbers following the DOT code are the Tire Identification Number (TIN). The TIN shows the manufacturer and plant code, tire size, and date the tire was manufactured. The TIN is molded onto both sides of the tire, although only one side may have the date of manufacture.

aspect ratio, construction type, and service description. See the “Tire Size” illustration later in this section for more detail. (B) TPC Spec (Tire Performance Criteria Specification): Original equipment tires designed to GM's specific tire performance criteria have a TPC specification code molded onto the sidewall. GM's TPC specifications meet or exceed all federal safety guidelines. (C) Dual Tire Maximum Load: Maximum load that can be carried and the maximum pressure needed to support that load when used in a dual configuration. For information on recommended tire pressure see Tire Pressure on page 10‑58
and Vehicle Load Limits on page 9‑16.

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Vehicle Care

(F) Tire Ply Material: The type of cord and number of plies in the sidewall and under the tread. (G) Single Tire Maximum Load: Maximum load that can be carried and the maximum pressure needed to support that load when used as a single. For information on recommended tire pressure see Tire Pressure on page 10‑58 and Vehicle Load Limits on page 9‑16.

Tire Designations

Tire Size The examples show a typical passenger vehicle and light truck tire size.

would mean that the tire's sidewall is 75 percent as high as it is wide. (D) Construction Code: A letter code is used to indicate the type of ply construction in the tire. The letter R means radial ply construction; the letter D means diagonal or bias ply construction; and the letter B means belted‐bias ply construction. (E) Rim Diameter: Diameter of the wheel in inches. (F) Service Description: These characters represent the load index and speed rating of the tire. The load index represents the load carrying capacity a tire is certified to carry. The speed rating is the maximum speed a tire is certified to carry a load.

Passenger (P‐Metric) Tire

(A) Passenger (P‐Metric) Tire: The United States version of a metric tire sizing system. The letter P as the first character in the tire size means a passenger vehicle tire engineered to standards set by the U.S. Tire and Rim Association. (B) Tire Width: The three‐digit number indicates the tire section width in millimeters from sidewall to sidewall. (C) Aspect Ratio: A two‐digit number that indicates the tire height‐to‐width measurements. For example, if the tire size aspect ratio is 75, as shown in item C of the tire illustration, it

GMC Sierra Owner Manual - 2012 - CRC - 11/15/11

Black plate (55,1)

(LT‐Metric) tire illustration, it would mean that the tire's sidewall is 75 percent as high as it is wide. (D) Construction Code: A letter code is used to indicate the type of ply construction in the tire. The letter R means radial ply construction; the letter D means diagonal or bias ply construction; and the letter B means belted‐bias ply construction. (E) Rim Diameter: Diameter of the wheel in inches. (F) Load Range: Load Range. (G) Service Description: The service description indicates the load index and speed rating of a tire. If two numbers are given as in the example, 120/116, then this represents the load index for single versus dual wheel usage

Vehicle Care

10-55

(single/dual). The speed rating is the maximum speed a tire is certified to carry a load.

Tire Terminology and