2007 GMC SIERRA CLASSIC Owners Manual

To get an accurate reading, the vehicle should be
on a level surface.
If the level is below the bottom of the ller plug
hole, located on the transfer case, you will need to
add some lubricant. Add enough lubricant to
raise the level to the bottom of the ller plug hole.
Use care not to overtighten the plug.
When to Change Lubricant
Refer to the Maintenance Schedule to determine
how often to change the lubricant. See
Scheduled Maintenance (Gasoline Engine) on
page 617.
What to Use
Refer to the Maintenance Schedule to determine
what kind of lubricant to use. SeeRecommended
Fluids and Lubricants on page 629.
Front Axle
When to Check Lubricant
It is not necessary to regularly check front axle
uid unless you suspect there is a leak or you hear
an unusual noise. A uid loss could indicate a
problem. Have it inspected and repaired.
Automatic Transfer Case
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How to Check Lubricant
To get an accurate reading, the vehicle should be
on a level surface.If the level is below the bottom of the ller plug
hole, located on the front axle, you may need
to add some lubricant:
When the differential is cold, add enough
lubricant to raise the level to 0 to 3/8 inch
(9.5 mm) below the ller plug hole.
When the differential is at operating
temperature (warm), add enough lubricant to
raise the level to the bottom of the ller
plug hole.
What to Use
To determine what kind of lubricant to use see
Recommended Fluids and Lubricants on page 629.
530

Noise Control System
Tampering with Noise Control
System Prohibited
The following information relates to compliance
with federal noise emission standards for vehicles
with a Gross Vehicle Weight Rating (GVWR) of
more than 10,000 lbs (4 536 kg). The Maintenance
Schedule provides information on maintaining
the noise control system to minimize degradation
of the noise emission control system during
the life of your vehicle. 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
specications.
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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.
Modication of the air cleaner.
Exhaust:

Removal of the muffler and/or resonator.
Removal of the exhaust pipes and exhaust
pipe clamps.
Bulb Replacement
For the proper type of replacement bulbs, see
Replacement Bulbs on page 541.
For any bulb changing procedure not listed in this
section, contact your dealer.
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.
532

Headlamps
To replace a headlamp bulb, do the following:
1. Open the hood. SeeHood Release on
page 479for more information.
2. Remove the two pins on the top of the
headlamp assembly. To remove the pins, turn
the outer pin outward and pull it straight up.
To remove the inner pin, turn it in and
pull it straight up.A. Low-Beam Headlamp
B. High-Beam Headlamp
3. Pull the headlamp assembly out.
4. Unplug the electrical connector.
5. Turn the old bulb counterclockwise and
remove it from the headlamp assembly.
6. Install the new bulb into the assembly and
turn it clockwise until it is tight.
7. Plug in the electrical connector.
8. Reinstall the headlamp assembly.
9. Reinstall and tighten the two pins.
533

Front Turn Signal, Sidemarker and
Daytime Running Lamps
A. Sidemarker Lamp
B. Retainer Clip
C. Front Turn Signal Lamp
D. Daytime Running Lamp (DRL)To replace a front turn signal, sidemarker or DRL
bulb, do the following:
1. Open the hood. SeeHood Release on
page 479for more information.
2. Remove the headlamp assembly as described
previously. SeeHeadlamps on page 533for
more information.
3. Press the retainer clip (B), located behind the
turn signal assembly, towards the outside of
the vehicle.
4. Pull the turn signal assembly out of the
vehicle.
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5. Press the locking release lever, turn the bulb
socket counterclockwise and remove it from
the turn signal assembly.
6. Remove the old bulb from the bulb socket.
7. Install a new bulb into the bulb socket.
8. Insert the bulb socket into the turn signal
assembly and turn it clockwise until it locks.
9. Reinstall the turn signal assembly back into
the vehicle placing the hook and posts on
the inner side into the alignment holes
rst, then the outer side into the retainer
bracket until you hear a click.
10. Reinstall the headlamp assembly.Roof Marker Lamps
To replace a roof marker lamp bulb, do the
following:
1. Remove the
two screws and
lift off the lens.
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2. Install a new bulb
into the socket and
turn it clockwise
until it locks
into place.
3. Reinstall the lens and tighten the screws.To replace a center roof marker lamp bulb, do the
following:
1. Remove the six screws from the center roof
marker lamp assembly.
2. Turn the old bulb counterclockwise to remove
it from the socket.
3. Reinstall the lens and tighten the screws.
536