1996 GMC Jimmy Owner's Manual - Page 127

If the LightIs Flashing NOTICE: If you keep driving your vehicle with this light on, after a while, youremission controls may not work as well, your fuel economy may not as be good and your engine may not runas smoothly. This could lead costly repairs that may not be to covered by your warranty. This light should come on, as a check to show you it is working, when the ignition is on and the engine is not running. If the light doesn't come on, have it repaired. This light will also come on during a malfunction in one of two ways: The following may prevent more serious damage to your vehicle: Reduce vehicle speed. Avoid hard accelerations. Avoid steep uphill grades. If towing a trailer, reduce the amount of cargo being hauled as soon as it is possible. If the light stops flashing and remains on steady, see "If the Light Is On Steady" following. If the light continues to flash, when it is safe to do so, stop the vehicle. Put your vehicle in PARK (P). Turn the key off, wait at least 10 seconds and restart the engine. If the light remains on steady, see "If the Light Is On Steady" following.If the light is still flashing follow the previous steps, and drive the vehicle to your dealer or qualified service center for service. Light Flashing -- A misfire condition has been detected. A misfire increases vehicle emissions and may damage the emission control system on your vehicle. Dealer or qualified service center diagnosis and service is required. 0 Light On Steady -- An emission control system malfunction has been detected on your vehicle. Dealer or qualified service center diagnosis and service may be required. 2-70