Normal Operation
WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
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 2 (CAN2) bus. If the RCM detects a fault with communications with the ABS module or CAN2 bus circuits, it will set 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.
- DTC U0028:08 (Vehicle Communication Bus A: Bus Signal / Message Failures) - When the RCM does not receive CAN2 bus messages from the ABS module for 5 seconds, a fault will be indicated. An open CAN2 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) - When the RCM detects the CAN2 circuits are shorted to ground, shorted to voltage or shorted to each other, a fault will be indicated.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- RCM
- ABS module