DIESEL FUEL SUPPLY/NO SHUT OFF INSTALL DIODE JUMPER WIRE

A CONDITION EXISTS WHEREBY AN ELECTRICAL FEEDBACK SIGNAL FROM THE ALTERNATOR CAN CAUSE THE ENGINE TO CONTINUE RUNNING WITH THE KEY IN THE OFF POSITION FOR VARIOUS PERIODS OF TIME. THE FEEDBACK SIGNAL PREVENTS THE INJECTION PUMP SOLENOID FROM SHUTTING OFF THE FUEL SUPPLY. THIS CONDITION IS FOUND ONLY IN 1983 G TRUCK VEHICLES EQUIPPED WITH THE 6.2L DIESEL AND THE BASE WARNING LIGHT SYSTEM (TELL-TALE LIGHTS). TO OVERCOME THIS ANNOYANCE, USE JUMPER WIRE, P/N 12038051. THIS WIRE INCORPORATES A DIODE WHICH PREVENTS A FEEDBACK SIGNAL. THIS HARNESS ASSEMBLY WILL BE INSTALLED IN PRODUCTION VEHICLES STARTING MARCH, 1983. USE THE FOLLOWING PROCEDURE TO INSTALL THIS WIRE 1.DISCONNECT THE NEGATIVE BATTERY CABLE FROM BOTH BATTERIES. 2.REMOVE THE ENGINE HARNESS BULKHEAD CONNECTOR. 3.LOOKING INTO THE TERMINAL END OF THE BULKHEAD CONNECTOR, LOCATE THE #25 CIRCUIT (BROWN WIRE) AND REMOVE. (SKETCH 1) 4.INSERT THE END OF THE JUMPER HARNESS INTO THE BULKHEAD CONNECTOR. (SKETCH 2) 5.USING THE SUPPLIED CONNECTOR, CONNECT THE OTHER END OF THE #25 CIRCUIT (BROWN WIRE) TO THE JUMPER HARNESS. 6.ATTACH THE BULKHEAD CONNECTOR. 7.RECONNECT BOTH NEGATIVE BATTERY CABLES. (ONE PAGE 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.