Test Z: The Engine Coolant Over Temperature Warning Indicator Is Never/Always On

PINPOINT TEST Z: THE ENGINE COOLANT OVER TEMPERATURE WARNING INDICATOR IS NEVER/ALWAYS ON

Z1-Z4:

Normal Operation
The PCM receives the engine coolant temperature status through hardwired circuitry from the ECT sensor (6.0L diesel engine), and from the cylinder head temperature (CHT) sensor (4.6L, 5.4L and 6.8L engines). The instrument cluster receives the engine coolant temperature data from the PCM over the high speed CAN. The instrument cluster monitors the engine coolant temperature data received from the PCM and when the engine coolant temperature is high, the engine over temperature warning indicator illuminates.

Possible Causes
- PCM
- Instrument cluster