Pinpoint Test N : U0121: Notes
WARNING: This page is about a different car, the 2017 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
Refer to Two Wheel Drive/Four Wheel Drive Systems for schematic and connector information.
Normal Operation
The TCCM sets the DTC U0121 when key messages such as wheel speed, brake pressure or torque are not received for longer than 5 seconds. This loss of key messages degrades the 4x4 system performance and/or inability to change 4x4 modes. Other modules that require data from the ABS module all set communication DTCs and may also exhibit system function concerns.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| U0121 | Lost Communication With Anti-Lock Brake System (ABS) Control Module | Sets in continuous memory in the TCCM if ABS data messages received from the ABS Module over the HS-CAN are missing for longer than 5 seconds. |
Possible Sources
- Communication concern
- Battery voltage concern
- ABS module
- TCCM