Component Tests and General Diagnostics

Chart C-16:

Wiring Diagram Chart C-16:

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


CIRCUIT DESCRIPTION:

The TEMP light is powered through the gauges fuse by ignition #1. The ECM illuminates the bulb by supplying a path to ground through quad-driver module 1 + 2(A).

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 turned "ON" while the engine is running and when the coolant temperature is above 120~C (248~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." See "coolant sensor temperature vs. resistance values"DTC 15 or compare coolant temperature reading on the scan tool with actual coolant temperature. Replace coolant temperature sensor if mis-scaled.