Test D: The Temperature Gauge Is Inoperative

PINPOINT TEST D: THE TEMPERATURE GAUGE IS INOPERATIVE

Normal Operation
The PCM uses the cylinder head temperature (CHT) sensor to measure the engine coolant temperature. 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 engine coolant temperature data is missing for 5 seconds or less or if instrument cluster receives invalid engine coolant temperature data 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 for more than 5 seconds, the instrument cluster sets DTC U0100 in continuous memory and defaults the temperature gauge to cold (C). If the engine coolant temperature data is deemed invalid by the instrument cluster for 5 seconds or more, the instrument cluster sets DTC U2199 and defaults the temperature gauge to cold (C).

NOTE: If DTC U0100 is set in the instrument cluster, other observable symptoms may be an inoperative tachometer, speedometer or odometer.

- DTC U2199 (Invalid Engine Coolant Temperature Data) - sets in continuous memory in the instrument cluster if the instrument cluster receives invalid engine coolant temperature data from the PCM for 5 seconds or more.

This pinpoint test is intended to diagnose the following:
- PCM concern
- Instrument cluster

D1-D4: