2010 GMC SIERRA DENALI Owners Manual

What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. SeeRecommended Fluids and
Lubricants on page 7‑11.
Front Axle
When to Check and Change Lubricant
It is not necessary to regularly check front axle fluid
unless you suspect there is a leak or you hear an
unusual noise. A fluid loss could indicate a problem.
Have it inspected and repaired.
How to Check Lubricant
To get an accurate reading, the vehicle should be on a
level surface.A : Fill Plug
B : Drain Plug
.When the differential is cold, add enough lubricant
to raise the level from 0 (0 mm) to 1/8 inch
(3.2 mm) below the filler plug hole.
.When the differential is at operating temperature
(warm), add enough lubricant to raise the level to
the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See Recommended Fluids and
Lubricants on page 7‑11.
6-51

Headlamp Aiming
The vehicle has a visual optical headlamp aiming
system. The aim of the headlamps have 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 your headlamps needs to
be adjusted.
It is recommended that the vehicle is taken to your
dealer/retailer for service if the headlamps need to be
adjusted. It is possible however, to re-aim the
headlamps as described.The vehicle should:.Be placed so the headlamps are 25 ft. (7.6 m) 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.
.Normally loaded with a full tank of fuel and one
person or 160 lbs (75 kg) sitting on the driver seat.
.Have the tires properly inflated.
.Have the spare tire is in its proper location in the
vehicle.
6-52

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 Release on page 6‑14
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) tothe 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.
6-53

7. Locate the vertical headlamp aiming screws, whichare under the hood near each headlamp assembly.
The adjustment screw can be turned with an
E8 Torx
®socket.
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.
6-54

Bulb Replacement
For the proper type of replacement bulbs, see
Replacement Bulbs on page 6‑60.
For any bulb changing procedure not listed in this
section, contact your dealer/retailer.
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.
Headlamps
To replace one of these bulbs:1. Open the hood. See Hood Release
on page 6‑14for more information.
2. If you are replacing the bulb on the passenger side remove the Engine Air Cleaner cover. See Engine
Air Cleaner/Filter
on page 6‑22for more
information.
3. Reach in and access the bulb sockets from inside the engine compartment.
6-55

4. Turn the bulb socket counterclockwise to remove itfrom 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.
6-56

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 bulbs by turning socket counterclockwise and pulling the bulb straight out.
3. Install the bulbs by pushing the bulb straight in and turning clockwise.
4. Reinstall the lamp assembly and tighten the screws.
6-57

Taillamps, Turn Signal, Stoplamps
and Back-up Lamps
To replace a taillamp bulb:1. Open the tailgate. See Tailgate
on page 3‑13for
more information.
2. Remove the two taillamp assembly
screws near the
tailgate latch.
A. Stoplamp/Turn Signal/Taillamp
B. Stoplamp/Turn Signal/Taillamp
C. Back-up Lamp
D. Sidemarker Lamp
3. Pull out the taillamp assembly.
6-58