Service All-Wheel Drive Light

This light should come on briefly when you turn on the ignition, as a check to show you it is working.
The service all-wheel drive light comes on to indicate that there may be a problem with the drive system and service is required. Malfunctions can be indicated by the system before any problem is apparent, which may prevent serious damage to the vehicle. This system is also designed to assist your GM dealer in correctly diagnosing a malfunction.
See also:
Service Parts Identification Label
This label, located either in the glove box or the trunk area, has the following information:
► Vehicle Identification Number (VIN).
► Model designation.
► Paint information.
...
Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from
short circuits by a combination of fuses and circuit
breakers. This greatly reduces the chance of fires
caused by electrical problems.
Loo ...
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 ...
