Tests AG: DTC U0100 - Lost Communication With ECM/PCM

PINPOINT TEST AG: DTC U0100 - LOST COMMUNICATION WITH ECM/PCM

AG1-AG5:

Normal Operation
The instrument cluster sets DTC U0100 in continuous memory if communication between the instrument cluster and the PCM results in missing data messages for the following systems or data types:

NOTE: For a complete list of all network messages, refer to Information Bus (Module Communications Network).

- Passive anti-theft system (PATS)
- Engine rpm
- Vehicle speed
- Transmission gear state
- Drive select
- Shift in progress
- Transmission internal fault
- Overdrive cancel
- Engine coolant temperature
- Odometer rolling count
- Fuel flow
- A/C pressure
- MIL telltale request
- Failsafe cooling mode
- Electronic throttle control (ETC)
- Charging system
- Speed control
- Check fuel cap
- A/C clutch engaged
- Timer engine off
- Vehicle information

Once the instrument cluster sets DTC U0100, multiple gauges or indicators are likely to be inoperative in the cluster. Other modules that require data from the instrument cluster all set communication DTCs and may also exhibit system function concerns.

Possible Causes
- Low battery voltage
- Communication network
- PCM