2002 GMC Envoy Owner's Manual - Page 156

Change Engine Oil Light Security Light United States Canada United States Canada This light is displayed when the engine oil needs to be changed. Once the engine oil has been changed, the CHANGE ENG OIL light must be reset. Until it is reset, the light will be displayed when the engine is on. For more information on resetting the system, see "Oil Life System" in the Index. If the light flashes, the PasslockR system has entered a tamper mode. If the vehicle fails to start, see "Passlock" in the Index. If the light comes on continuously while driving and stays on, there may be a problem with the Passlock system. Your vehicle will not be protected by Passlock, and you should see your dealer. Also, see "Content Theft-Deterrent" in the Index for additional information regarding the SECURITY light. This light will come on briefly when you turn the key toward START. The light will stay on until the engine starts. 2-87