Chart C-16 PCM Controlled Temp Lamp Circuit

Chart C-16:

PCM Controlled Temp Lamp Wiring Circuit:

Circuit Description:
The "Temp" lamp is connected to battery voltage through the ignition switch. The PCM energizes the bulb by supplying a path to ground through Quad-Driver Module 1 (QDSM).

Chart Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.
1. With the ignition "ON" and engine "OFF," the PCM should be grounding CKT 35.
2. While the engine is running, the "Temp" lamp should be turned "ON" by the PCM only when the engine coolant temperature is above 123°C (253°F). The "Temp" lamp should be turned "OFF" when the engine is running and the engine coolant temperature goes lower than 12O°C (249°F).

Diagnostic Aids: The engine coolant temperature sensor, in rare cases, may fail to indicate the correct engine coolant temperature without setting a DTC. This could result in turning "ON" the "Temp" lamp without having an overheating condition. It could also result in overheating without the "Temp" lamp 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.

Any circuit that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections, corroded terminals and/or wiring, or physical damage to the wiring harness.