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:
Automatic Transmission
The automatic transmission has a shift lever located on the console between the
seats.
The selected gear is also shown in the instrument cluster.
P (Park): This position locks the drive wheels ...
Power Steering
If power steering assist is lost because the engine stops
or the system is not functioning, the vehicle can be
steered but it will take more effort. ...
If the Light is Flashing
The following may prevent more serious damage
to your vehicle:
• Reducing vehicle speed
• Avoiding hard accelerations
• Avoiding steep uphill grades
• If you are towing a trailer, reduc ...
