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

MODELS AFFECTED: 19831/2 3.8L Regals, 3.0L Centurys

Should a condition of code 42 being set in a 1983 1/2 Regal 3.8L or Century 3.0L, it could be caused by an EST harness being routed too close to the spark plug wires. This may cause EST signals sent from the ECM to be interrupted by the electro magnetic field created by spark plugs firing. To correct this condition the following procedure should be used.

3.8L Regals LD5 engine

Route No. 2, 4, and 6 spark plug wires to the inside of the engine lift hook and the EST harness under and around the distributor, as shown in the illustration. Also make sure that the TPS and ISC harnesses are routed below the canister purge hose.

3.0L CENTURY LK9 ENGINE

Ensure the EST harness from the distributor runs under the distributor and heater hose and is tie wrapped around the alternator support as shown in this illustration.

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.