Transmission Control Module (TCM) - AS68RC

U0121-LOST COMMUNICATION WITH ANTI-LOCK BRAKE MODULE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Transmission Control Module (TCM) continuously monitors the Bus activity and receives the messages it needs.

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:
- ABS CAN C Bus message has not been received for 500 ms.

Refer to DTC Based Diagnostics and Non DTC Based Diagnostics for diagnostic procedures and other possible causes.