Pinpoint Test Z: The Engine Over-Temperature Message Center Warning Indicator Is Never/Always On
Instrumentation, Message Center and Warning Chimes
Pinpoint Test Z: The Engine Over-Temperature Message Center Warning Indicator Is Never/Always On
Normal Operation
The PCM uses the Cylinder Head Temperature (CHT) sensor to monitor the engine temperature. The Instrument Cluster (IC) receives the engine temperature data from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. The IC monitors the engine temperature data received from the PCM and commands the engine over-temperature message center warning indicator on or off.
Failsafe Cooling
The PCM provides 2 modes or levels of failsafe cooling, which provides a visual indication to the driver that the engine is overheating while reducing the engine power to lower the engine temperature. When the PCM sends the IC a failsafe mode-1 command, the IC turns on the engine over-temperature message center warning indicator. When the PCM sends the IC a failsafe cooling mode-2 command, the IC flashes the engine over-temperature message center warning indicator.
If the engine over-temperature status message is missing or invalid for less than 5 seconds, the engine over-temperature warning indicator remains in the last on/off state, based upon the last known good engine over-temperature status message received.
If the engine over-temperature status message is missing for more than 5 seconds, the IC sets DTC U0100 in continuous memory and defaults the engine over-temperature warning indicator on.
If the engine coolant temperature data is invalid for more than 5 seconds, the IC sets DTC U2199 and defaults the engine over-temperature message center warning indicator on.
NOTE: If DTC U0100 is set in the IC, other observable symptoms may be an inoperative tachometer, temperature gauge or odometer.
This pinpoint test is intended to diagnose the following:
- Engine over-temperature concern
- PCM
PINPOINT TEST Z: THE ENGINE OVER-TEMPERATURE MESSAGE CENTER WARNING INDICATOR IS NEVER/ALWAYS ON
