GM Service Manual Online
For 1990-2009 cars only

INTER. CHECK ENGINE LIGHT ENGINE WIRE HARNESS ROUTING

IT IS IMPORTANT THAT THE ENGINE WIRE HARNESS ROUTING ON THE 1981 OMEGA MODELS WITH A 2.5L BE CORRECT TO PREVENT DISTURBANCES IN THE COMPUTER COMMAND CONTROL SYSTEM. THE WIRE HARNESS FROM THE STARTER IS ROUTED AROUND THE FRONT (LEFT) OF THE ENGINE AND PASSES UNDER THE INTAKE MANIFOLD BEHIND THE DISTRIBUTOR. IF ROUTED TO CLOSE TO THE DISTRIBUTOR , INTERMITTENT "CHECK ENGINE" LIGHT AND ERRATIC TIMING AND DWELL READINGS CAN OCCUR WHENEVER HEAVY ELECTRICAL LOADS ARE TURNED ON (IE. LIGHTS, DEFOGGER ETC.) IF THE CONDITION IS ELIMINATED BY UNPLUGGING THE ALTERNATOR, THE WIRE ROUTING SHOULD BE CHECKED AT THE HARNESS CLIP BEHIND THE DISTRIBUTOR. IF THIS CLIP IS INSTALLED 180F OUT OF POSITION IT WILL HOLD THE WIRE HARNESS TOO CLOSE TO THE DISTRIBUTOR (FIG. 12).

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.