2005 GMC Envoy Owner's Manual - Page 183

Service Four-Wheel Drive Warning Light This light should come on briefly when you turn on the ignition, as a check to show you it is working. Check Gages Warning Light The check gages light will come on briefly when you are starting the engine. The service four-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. 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. Gate Ajar Light If this light comes on, your liftgate or liftglass is not completely shut. Close the liftgate or liftglass. Never drive with the liftgate or liftglass even partially open. 3-47