2004 GMC Envoy Owner's Manual - Page 169

The SERVICE 4WD 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 service technician in correctly diagnosing a malfunction. Gate Ajar Light Check Gages Warning Light United States Canada If this light comes on, your liftgate or liftglass is ajar. Try closing the liftgate or liftglass again. Never drive with the liftgate or liftglass even partially open. United States Canada The CHECK GAGES light will come on briefly when you are starting the engine. If the light comes on and stays on while you are driving, check your coolant temperature and engine oil pressure gages to see if they are in the warning zones. 3-49