U1120

U1120-LOST WHEEL DISTANCE MESSAGE

U1120-Lost Wheel Distance Message:

WHEN MONITORED
Ignition on.

SET CONDITION
The PCM doesn't receive a wheel distance message from the Anti-lock brake Module or FCM (NON-ABS) over the CAN C bus.

POSSIBLE CAUSES
- CAN C BUS circuit open or shorted
- Anti-lock brake module
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Theory of Operation
The PCM receives the vehicle speed signal over the CAN C bus from the Anti-lock Brake Module or FCM (NON-ABS).

Diagnostic Test

1. ACTIVE DTC

Ignition on, engine not running.
With the scan tool read Powertrain DTCs.

Q: Is the DTC active at this time?

YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

2. U0121-LOST COMMUNICATION WITH ABS MODULE/P0141-LOST COMMUNICATION WITH FCM ALSO SET

NOTE: If the vehicle is not equipped with ABS the VSS signal will come from the FCM.

With the scan tool, read the appropriate module for DTCs.

Q: Is the U0121-LOST COMMUNICATION WITH ABS MODULE/PO141-Lost Communicate With FCM also set?

YES: Perform the appropriate diagnostic test. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Replace and program the Powertrain Control Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test