Component Tests and General Diagnostics

Chart C-16:

Chart C-16 Wiring Diagram:

***UPDATED BY TSB # 92-U-35A DATED OCTOBER 1992



CIRCUIT DESCRIPTION:


The TEMP light or optional "Check Gauges" light is connected to battery voltage through the ignition switch. The ECM illuminates the bulb by supplying a path to ground through quad-driver module #2.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. With the ignition "ON" and engine "OFF," the ECM should be grounding circuit 35.

2. The TEMP light should only be controlled to be turned "ON" while the engine is running when the coolant temperature is above 123~C (253~F). While the engine is running, the "TEMP" light or optional "Check Gauges" light should be turned "ON" by the ECM only when the coolant temperature is above 123~C (253~F). The "TEMP" light or "Check Gauges" light should be turned "OFF" when the engine is running and the coolant temperature goes lower than 120~C (249~F).

DIAGNOSTIC AIDS


^ The coolant temperature sensor, in rare cases, may fail to indicate the correct engine coolant temperature without setting a malfunction code. This could result in turning "ON" the TEMP light without having a overheating condition. It could also result in overheating without the "Temp"/"Check Gauges" light being turned "ON."

^ An intermittent problem may be caused by a poor or corroded connection, rubbed through wire connection, a wire that is broken inside the insulation or a corroded wire. Technician should check condition of connector and sensor terminals for corrosion, and clean and/or replace as necessary. If corrosion is found, check condition of connector seal and repair or replace if necessary. Check also for backed out terminals inside connectors.

^ - Intermittent Malfunctions