Pinpoint Test 3: The Temperature Gauge Is Inoperative

PINPOINT TEST 3: THE TEMPERATURE GAUGE IS INOPERATIVE

Normal Operation

The PCM uses the engine coolant temperature (ECT) sensor to measure the engine coolant temperature on the 3.0L engine and the cylinder head temperature (CHT) sensor on the 2.5L engine. The instrument cluster receives the engine coolant temperature data from the PCM over the high speed controller area network (HS-CAN) communication bus. The instrument cluster monitors the engine coolant temperature data received from the PCM and commands the temperature gauge indication with a corresponding movement of the pointer.If the instrument cluster receives invalid engine coolant temperature data from the PCM for 5 seconds or less, the instrument cluster defaults the temperature gauge to the last setting, based upon the last known good temperature status message. If the instrument cluster does not receive the engine coolant temperature status message from the PCM or if the data received is deemed invalid for more than 5 seconds, the instrument cluster sets DTC U0100 in continuous memory and defaults the temperature gauge to cold (C).

Possible Causes
- PCM concern
- Instrument cluster

Diagnostic Procedure