CODE 42 ERROR-FALSE SIGNAL TO EST HARNESS/REROUTE PLUG WIRES

A condition of Trouble Code 42 being set on 1983 Bonneville or Grand Prix vehicles equipped with the 3.8L V-6 engine (VIN Code A) could be caused by the EST harness being routed too close to a spark plug wire. This may cause EST signals sent from the ECM to be interfered with by electro-magnetic fields created by a spark plug firing.

To correct this condition, route #2, #4 and #6 spark plug wires around the inside of the engine lift hook and the EST harness under and around the distributor (see illustration). In addition, make sure the TPS and ISC harnesses are routed below the canister purge hose.

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.