Accessory Signal: Description and Operation

DESCRIPTION
Vehicles equipped with the standard Instrument Panel (I/P) cluster utilize a "Temp" warning lamp that indicates an overheating condition of the engine.

Vehicles equipped with the optional (UB3) gauges I/P cluster, utilize a "Check Gauges" warning lamp that indicates an overheating condition, low fuel level, low oil pressure or low generator output.


OPERATION
The "Temp/Check Gauges" lamp receives batters voltage from the ignition switch through the gauges fuse. The Powertrain Control Module (PCM) controls it by providing a ground path to energize the bulb. The bulb is energized whenever the ignition switch is in the "ON" position and the engine is not running. This is for checking the bulb.

The "Temp/Check Gauges" lamp is illuminated while the engine is running if the engine coolant temperature exceeds 123° C (253° F) and no Engine Coolant Temperature (ECT) sensor malfunction Diagnostic Trouble Codes (DTC)'s (14 and 15) have been set

The "Temp/Check Gauges" lamp is turned "OFF" when the engine coolant temperature goes below 120° C (248° F).

CHECK GAUGES LAMP
The optional "Check Gauges" warning lamp is activated in the same way as the "Temp" warning lamp described above. In addition, it may be turned "ON" by the fuel gage, oil pressure gage, or volt gage.