AS68RC Automatic Transmission

U0100-LOST COMMUNICATION WITH ECM / PCM

For a complete wiring diagram refer to Diagrams/Electrical. Electrical Diagrams


Theory of Operation


The Transmission Control Module (TCM) continuously monitors the Bus activity and receives the messages it needs. The CAN C Bus is also used to communicate transmission MIL status to the Engine Controller. If the Engine Controller is unable to communicate with the Transmission Controller, the Engine Controller will light the MIL.



- When Monitored:

No CAN Bus performance codes present. Input speed is greater than 300 rpm when the shift lever is in Park or Neutral or the Transmission range sensor indicates drive and pressure switch 8 is closed when the shift lever is in Drive, Third, Second, or Low. Battery voltage greater than 10 volts but less than 16 volts. Conditions must be present continuously for 5 seconds.

- Set Condition:

PCM CAN C Bus message has not been received for 500 ms.

Refer to Communications for diagnostic procedures and for further possible causes.