DIESEL GLOW PLUG BURNED OUT QUICK CHECK PROCEDURE

THE THERMAL CONTROLLER REQUIRES FEEDBACK FROM THREE SOURCES TO DETERMINE THE "ON-OFF" CYCLE TIME OF THE GLOW PLUGS. A CYCLE TIME THAT IS TOO LONG WILL CAUSE THE PLUGS TO BURN OUT PREMATURELY. THIS CONDITION IS SHOWING UP AFTER ENGINE CHANGES, WHICH SUGGEST THAT WIRES OR CONNECTORS ARE BEING DAMAGED. A QUICK SYSTEM CHECK CAN BE MADE BY PROBING THE WIRES AT THE THERMAL CONTROLLER WITH A TEST LIGHT AS OUTLINED BELOW: 1. COLD ENGINE, TURN KEY ON AND PROBE THE ORANGE WIRE, THE TEST LIGHT SHOULD CYCLE ON AND OFF WITH THE GLOW PLUGS. 2. PROBE THE BROWN WIRE, START THE ENGINE, GENERATOR OUTPUT WILL CAUSE THE LIGHT TO COME ON. 3. ENGINE WARM AND NOT RUNNING, KEY ON, AND PROBE THE BROWN WIRE. CURRENT FLOW THROUGH THE COOLANT TEMPERATURE SWITCH WILL CAUSE THE LIGHT TO COME ON.

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.