1995 GMC Jimmy Owner's Manual - Page 124

Malfunction Indicator Lamp (SERVICE ENGINE SOON Light) 7 SERVICE ENGINE SOON b The amber Malfunction Indicator Lamp (SERVICE ENGINE SOON Light) is located at the top of your instrument panel. A computer monitors operation of your fuel, ignition and emission control systems. This light should comeon when the ignition is but the engine is on, not running, as a check to show you it is working. If it does not come on at all, have it fixed right away.If it stays on, or it comes on while you are driving, the computer is indicating that you have problem. You should a take your vehicle in for service soon. NOTICE: If you keep driving your vehicle with this lightafter awhile on, the emission controls won't work well, your fuel economy as as smoothly. This won't beas good and your engine may not run by could leadto costly repairs not covered your warranty. If Your Vehicle is Equipped with OBD I! Certain vehicles are equipped with new emission diagnostic system. You a can tell whether your vehicle has this system by reading your tune-up label located under the hood. If the label says "OBD 11" on it, the following instructions apply. Malfunction IndicatorLamp (SERVICE ENGINE SOON Light) Your vehicle is equipped with an onboard computer which monitors operation of the emission controlsystem. This system is called OBD I1 (On-Board Diagnostics-Second Generation) and is intended to assure that emissions are at acceptable levels for the life of the vehicle, helping to produce a cleaner environment. The "SERVICE ENGINESOON'' light comes on to indicate when service is required. Malfunctions often will be 2-72