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 airbag warning indicator if either DTC U0028:08 or U0028:88 is set.

• DTC U0028:08 (Vehicle Communication Bus A: Bus Signal/Message Failures) - A fault is indicated when the RCM  does not receive dedicated CAN  messages from the ABS module for 5 seconds. An open dedicated CAN  circuit, incorrectly 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) - A fault is indicated when the RCM  detects the dedicated CAN  circuits are shorted to ground, shorted to voltage or shorted to each other.

This pinpoint test is intended to diagnose the following: 

• Wiring, terminals or connectors
• RCM 
• ABS module