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Home >> Lincoln >> 2018 >> MKZ Select, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 615 (Auxiliary Brake System) >> Diagnosis And Testing >> Auxiliary Brake System - Trailer Brake Control (TBC) Module >> Pinpoint Tests >> Pinpoint Test H : DTC U0121:00 >> Notes

Pinpoint Test H : DTC U0121:00: Notes

WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

Normal Operation and Fault Conditions 

With the ignition ON, the ABS module sends messages to the TBC module over the HS-CAN. If the TBC module does not receive these messages within a certain time frame, the TBC module sets DTCs. For information on the messages sent to the TBC module by the ABS module, refer to the Network Message Chart in Description and Operation.

DTC Fault Trigger Conditions 

DTC Description Fault Trigger Conditions
U0121:00 Lost Communication With Anti-Lock Brake System (ABS) Control Module: No Sub Type Information This DTC sets in continuous memory when any of the messages from the ABS module is missing. This can be due to an ABS module failure, a circuit failure on the HS-CAN or an excessive load on the network.
U0415:81 Invalid Data Received From Anti-Lock Brake System (ABS) Control Module: Invalid Serial Data Received This DTC sets in continuous memory when the brake torque message required for adaptive cruise control braking and collision mitigation by braking contains a value either of "Unknown" or "Fault" instead of the actual brake torque information. This can be due to an ABS module failure, a circuit failure on the HS-CAN or an excessive load on the network.

Possible Causes