Normal Operation
The Restraints Control Module (RCM) supplies the stability/traction control system with the yaw rate, roll rate, lateral and longitudinal accelerometer over a dedicated Controller Area Network (CAN). If the RCM detects a fault with communications with the ABS module or dedicated CAN circuits, it sets DTC U0028:08 or U0028:88.
The RCM does not request the Instrument Panel Cluster (IPC) to illuminate the air bag warning indicator if either DTC U0028:08 or U0028:88 is set. The air bag warning indicator remains off if either of these DTCs are set.
- DTC U0028:08 (Vehicle Communication Bus A: Bus Signal/Message Failures) - When the RCM does not receive dedicated CAN bus messages from the ABS module for 5 seconds, a fault is indicated. An open dedicated CAN circuit, incorrect installed ABS module or loss of power and/or ground to the ABS module can set this DTC.
- DTC U0028:88 (Vehicle Communication Bus A: Bus Off) - When the RCM detects the dedicated CAN circuits are shorted to ground, shorted to voltage or shorted to each other, a fault is indicated.
The ABS module may set similar DTCs, U0151 (Lost Communication With Restraints Control Module) and U0452 (Invalid Data Received From Restraints Control Module).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- RCM
- ABS module