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In addition, the vehicle may have a passenger
sensing system for the right front passenger
position, which includes sensors that are part of
the passenger seat. The passenger sensing system
may not operate properly if the original seat trim is
replaced with non-GM covers, upholstery or trim, or
with GM covers, upholstery or trim designed for a
different vehicle. Any object, such as an aftermarket
seat heater or a comfort enhancing pad or device,
installed under or on top of the seat fabric, could also
interfere with the operation of the passenger sensing
system. This could either prevent proper deployment
of the passenger airbag(s) or prevent the passenger
sensing system from properly turning off the
passenger airbag(s). SeePassenger Sensing
System on page 1-70.
If you have any questions about this, you should
contact Customer Assistance before you modify the
vehicle. The phone numbers and addresses for
Customer Assistance are in Step Two of the
Customer Satisfaction Procedure in this manual.
SeeCustomer Satisfaction Procedure on page 7-2.
If the vehicle has rollover roof-rail airbags, see
Different Size Tires and Wheels on page 5-73for
additional important information.Q:Because I have a disability, I have to get my
vehicle modi ed. How can I nd out whether
this will affect my airbag system?
A:If you have questions, call Customer Assistance.
The phone numbers and addresses for Customer
Assistance are in Step Two of the Customer
Satisfaction Procedure in this manual. See
Customer Satisfaction Procedure on page 7-2.
In addition, your dealer/retailer and the service manual
have information about the location of the airbag
sensors, sensing and diagnostic module and airbag
wiring.
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Page 133 of 408

Automatic Headlamp System
When it is dark enough outside and the headlamp
switch is in AUTO, the automatic headlamp system turns
on the headlamps, along with the taillamps, sidemarker,
parking lamps, roof marker lamps, and the instrument
panel lights. The radio lights will also be dim.
To turn off the automatic headlamp system, turn the
exterior lamps switch to the off position and then release.
For vehicles first sold in Canada, the transmission must
be in the P (Park) position, before the automatic
headlamp system can be turned off.
The vehicle has a light sensor located on the top of
the instrument panel. Do not cover the sensor or
the system will come on whenever the ignition is on.
The system may also turn on the headlamps when
driving through a parking garage or tunnel.
There is a delay in the transition between the daytime
and nighttime operation of the Daytime Running Lamps
(DRL) and the automatic headlamp systems so that
driving under bridges or bright overhead street lights does
not affect the system. The DRL and automatic headlamp
system is only affected when the light sensor sees a
change in lighting lasting longer than the delay.If the vehicle is started in a dark garage, the automatic
headlamp system comes on immediately. Once the
vehicle leaves the garage, it takes approximately
30 seconds for the automatic headlamp system to
change to DRL if it is light outside. During that delay,
the instrument panel cluster may not be as bright
as usual. Make sure the instrument panel brightness
control is in the full bright position. SeeInstrument
Panel Brightness on page 3-15.
Instrument Panel Brightness
The knob for this feature is located next to the exterior
lamps control.
D(Instrument Panel Lights):Push knob to extend
and then turn clockwise or counterclockwise to brighten
or dim the instrument panel lights and the radio display.
This only works if the headlamps or parking lamps are on.
To turn on the dome lamps, with the vehicle doors
closed, turn the knob all the way clockwise.
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Page 166 of 408

To calibrate the compass, use the following procedure:
Compass Calibration Procedure
1. Before calibrating the compass, make sure the
compass zone is set to the variance zone in
which the vehicle is located. See “Compass
Variance (Zone) Procedure” earlier in this section.
Do not operate any switches such as window,
sunroof, climate controls, seats, etc. during
the calibration procedure.
2. Press the vehicle information button until
PRESS
VTO CALIBRATE COMPASS displays.
3. Press the set/reset button to start the compass
calibration.
4. The DIC will display CALIBRATING: DRIVE IN
CIRCLES. Drive the vehicle in tight circles at
less than 5 mph (8 km/h) to complete the calibration.
The DIC will display CALIBRATION COMPLETE
for a few seconds when the calibration is complete.
The DIC display will then return to PRESS
VTO
CALIBRATE COMPASS.
DIC Warnings and Messages
Messages are displayed on the DIC to notify the driver
that the status of the vehicle has changed and that
some action may be needed by the driver to correct
the condition. Multiple messages may appear one after
another.
Some messages may not require immediate action, but
you can press any of the DIC buttons on the instrument
panel to acknowledge that you received the messages
and to clear them from the display.
Some messages cannot be cleared from the DIC
display because they are more urgent. These messages
require action before they can be cleared. You should
take any messages that appear on the display seriously
and remember that clearing the messages will only
make the messages disappear, not correct the problem.
The following are the possible messages that can be
displayed and some information about them.
If your vehicle has the DURAMAX
®Diesel engine, see
the DURAMAX®Diesel manual for more information.
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Page 295 of 408
Center High-Mounted
Stoplamp (CHMSL)
The Center High-Mounted Stoplamp (CHMSL) is located
above the rear doors at the center of the vehicle.
To replace a bulb:
1. Remove the two screws from the CHMSL assembly.
2. Remove the CHMSL assembly.
3. Turn the bulb counterclockwise one quarter turn to
remove it from the socket.
4. Turn the bulb clockwise one quarter turn to install it
in the socket.
5. Reinstall the CHMSL assembly and two screws.
Do not block or damage the CHMSL when items
are loaded on the roof of the vehicle.
Taillamps
To replace one of these bulbs:
1. Remove the two
inboard nuts from the
inside of the taillamp
assembly.
2. Pull the taillamp assembly straight back to clear the
studs.
3. Slide the taillamp assembly slightly upward to
release the lower clip.
4. Remove the three nuts on the taillamp assembly.
5. Remove the taillamp assembly from the vehicle.
5-51