GMC SIERRA 2008 Owner's Manual

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.
Bulb Replacement
For the proper type of replacement bulbs, see
Replacement Bulbs on page 5-65.
For any bulb changing procedure not listed in this
section, contact your dealer/retailer.
Halogen Bulbs
{CAUTION:
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.
5-59

Headlamps
To replace one of these bulbs:
1. Open the hood. SeeHood Release on page 5-13
for more information.
2. If you are replacing the bulb on the passenger side
remove the Engine Air Cleaner cover. SeeEngine
Air Cleaner/Filter (Gasoline Engines) on page 5-19
for more information.
3. Reach in and access the bulb sockets from inside
the engine compartment.
4. Turn the bulb socket counterclockwise to remove it
from the headlamp assembly and pull it straight out.
5. Unplug the electrical connector from the old bulb by
releasing the clips on the bulb socket.
6. Replace it with a new bulb socket.
7. Plug in the electrical connector to the new
bulb socket.
8. Reinstall the new bulb socket into the headlamp
assembly and turn it clockwise to secure.
9. Close the hood.
5-60

Center High-Mounted Stoplamp
(CHMSL) and Cargo Lamp
To replace one of these bulbs:
1. Remove the screws and lift off the lamp assembly.A. Cargo Lamp
B. Center High-Mounted Stoplamp Bulb (CHMSL)
2. Remove the CHMSL and Cargo bulbs by turning
socket counterclockwise and pulling the bulb
straight out.
3. Install the CHMSL and Cargo bulbs by pushing the
bulb straight in and turning clockwise.
4. Reinstall the lamp assembly and tighten the screws.
5-61

Pickup Box Identication and
Fender Marker Lamps
To replace a pickup box identication or fender marker
lamp bulb:
1. Press the tab from the back to remove the lamp.
2. Unplug the lamp assembly harness.
3. Gently pry the individual lamp from the lamp
assembly.
4. Unplug the lamp.
5. Plug in a new lamp and snap it into the assembly.
6. Reinstall the lamp assembly.
Taillamps, Turn Signal, Stoplamps
and Back-up Lamps
To replace one of these bulbs:
1. Open the tailgate.Tailgate on page 2-14for more
information.
2. Remove the two rear
lamp assembly screws
near the tailgate latch
strikerpost and pull out
the lamp assembly.
3. Determine which of the following taillamp
assemblies applies to your vehicle.
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A. Stoplamp/Taillamp/Turn Signal Lamp
B. Back-up Lamp
C. Stoplamp/Taillamp/Turn Signal Lamp
4. Press the tab, if the vehicle has one, and turn the
bulb socket counterclockwise to remove it from the
taillamp assembly.A. Stoplamp/Taillamp/Turn
Signal Lamp
B. Stoplamp/Taillamp/Turn
Signal LampC. Back-up Lamp
D. Sidemarker Lamp
5. Pull the old bulb straight out from the socket.
6. Press a new bulb into the socket and turn the socket
clockwise into the taillamp assembly.
7. Reinstall the taillamp assembly. Dually Models
All Other Models
5-63

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.
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.
License Plate Lamp
To replace one of these bulbs:
1. Reach under the rear bumper for the bulb socket.
2. Turn the bulb socket counterclockwise and pull the
bulb socket out of the connector.
3. Pull the old bulb from the bulb socket, keeping the
bulb straight as you pull it out.
4. Install the new bulb.
5. Reverse Steps 1 through 3 to reinstall the
bulb socket.
5-64

Replacement Bulbs
Exterior Lamp Bulb Number
Back-up Lamp 3047
Back-up Lamp* 1156
Cargo Lamp and Center
High-Mounted Stoplamp (CHMSL)912
Fender Marker and Front Roof
MarkerW5WLL
Front Parking and Turn Lamp 3457A
High-Beam Headlamp 9005
Low-Beam Headlamp H11
License Plate Lamp 168
Stoplamp/Taillamp/Turn Signal Lamp 3047
Sidemarker Lamp 194
Stoplamp/Turn Signal Lamp/
Taillamp*1157
* Chassis Cab Models
For replacement bulbs not listed here, contact your
dealer/retailer.
Windshield Wiper Blade
Replacement
Windshield wiper blades should be inspected for wear
or cracking. SeeScheduled Maintenance (Gasoline
Engine) on page 6-4for more information on wiper blade
inspection.
Replacement blades come in different types and are
removed in different ways. Here is how 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.
5-65

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, seeMaintenance
Replacement Parts on page 6-17.
Tires
Your new vehicle comes with high-quality tires
made by a leading tire manufacturer. If you ever
have questions about your tire warranty and where
to obtain service, see your vehicle Warranty
booklet for details.
{CAUTION:
Poorly maintained and improperly used
tires are dangerous.
Overloading your vehicle’s tires can
cause overheating as a result of too
much exing. You could have an
air-out and a serious accident. See
Loading Your Vehicle on page 4-36.
Underinated tires pose the same
danger as overloaded tires. The
resulting accident could cause serious
injury. Check all tires frequently to
maintain the recommended pressure.
Tire pressure should be checked when
your vehicle’s tires are cold. See
Inflation - Tire Pressure on page 5-74.
Overinated tires are more likely to be
cut, punctured, or broken by a sudden
impact — such as when you hit a
pothole. Keep tires at the
recommended pressure.
Worn, old tires can cause accidents. If
the tire’s tread is badly worn, or if
your vehicle’s tires have been
damaged, replace them.
5-66

20-Inch Tires
If your vehicle has the optional 20-inch
P275/55R20 size tires, they are classied as
touring tires and are designed for on road use. The
low-prole, wide tread design is not recommended
for “off-road” driving or commercial uses such as
snow plowing. SeeOff-Road Driving on page 4-12
andAdding a Snow Plow or Similar Equipment on
page 4-43for additional information.
Tire Sidewall Labeling
Useful information about a tire is molded into the
sidewall. The following illustrations are examples
of a typical P-Metric and a LT-Metric tire sidewall.
(A) Tire Size
:The tire size code is a combination
of letters and numbers used to dene 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.
Passenger (P-Metric) Tire
5-67

(B) TPC Spec (Tire Performance Criteria
Specication):Original equipment tires designed
to GM’s specic tire performance criteria have a
TPC specication code molded onto the sidewall.
GM’s TPC specications 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 Identication Number (TIN)
:The letters
and numbers following DOT code are the Tire
Identication 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 5-86.(G) Maximum Cold Ination Load
Limit
:Maximum load that can be carried and the
maximum pressure needed to support that load.
For information on recommended tire pressure see
Inflation - Tire Pressure on page 5-74andLoading
Your Vehicle on page 4-36.
Light Truck (LT-Metric) Tire
5-68