GMC 2006 Sierra 1500 Pickup Owner's Manual page 239

SERVICE 4WD (Four-Wheel-Drive)
If a problem occurs with the four-wheel-drive system,
this message will appear on the DIC. If this message
appears, stop as soon as possible and turn off the
vehicle. Restart the vehicle and check for the message
on the DIC display. If the message is still displayed
or appears again when you begin driving, the
four-wheel-drive system needs service. See your
GM dealer.
SERVICE AIRBAG
If there is a problem with the airbag system, this message
will be displayed on the DIC. Have your GM dealer
inspect the system for problems. See Airbag Readiness
Light on page 3-35 and Airbag System on page 1-70 for
more information. Pressing any of the four DIC buttons
will acknowledge the message and clear it from the
DIC display. If your vehicle does not have the four DIC
buttons, pressing the trip odometer reset stem will
acknowledge the message and clear it from the
DIC display.
SERVICE BRAKE BOOSTER
CAUTION:
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Your brake system may not be working
properly if the SERVICE BRAKE BOOSTER
message is displayed.
If the brake system warning light is also on,
you should have the vehicle towed for service.
See Brake System Warning Light on page 3-41.
If the brake system warning light is not on, you
still have brakes, but the supplemental brake
assist system on vehicles with rear disc brakes
may not operate properly. In the event of a
vacuum loss, you may not have vacuum power
assist for braking. The brake pedal will be
harder to push and it will take longer to stop.
If you continue to drive with this message
displayed it can lead to a crash. Have the
brake system serviced as soon as possible.
If your vehicle has vacuum assist power brakes, this
message will be displayed on the DIC when there is a
problem with the Supplemental Brake Assist system.
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