Pinpoint Test AU: Lost Communication With Abs: Notes

Refer to appropriate Supplemental Restraint System in OEM Wiring Diagrams article, for schematic and connector information.

Normal Operation and Fault Conditions

The RCM supplies the stability/traction control system with the yaw rate, roll rate, lateral and longitudinal accelerometer over a dedicated HS-CAN bus. If the RCM detects a fault with communications with the ABS module or dedicated CAN bus circuits, it sets DTC U0028:08 or U0028:88.

The RCM does not request the IPC to illuminate the airbag warning indicator if either DTC U0028:08 or U0028:88 is set.

PPT AU RCM DTC FAULT TRIGGER CONDITIONS

DTC	Description	Fault Trigger Conditions
U0028:88	Vehicle Communication Bus A: Bus Off	Sets when the RCM detects the dedicated CAN circuits are shorted to ground, shorted to voltage or shorted to each other.

Possible Causes

Wiring, terminals or connectors
PAD switch
RCM

WARNING: Incorrect repair techniques or actions can cause an accidental SRS deployment. Never compromise or depart from these instructions. Failure to precisely follow all instructions could result in serious personal injury from an accidental deployment.

CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.

NOTE: Only disconnect or reconnect SRS components when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS.

NOTE: Always make sure the correct OCSM component is being installed. Parts released for other vehicles may not be compatible even if they appear physically similar. Check the part number listed in the Ford parts catalog to make sure the correct component is being installed. If an incorrect OCSM component is installed, DTCs may set.

NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.

Restraint Control Module-B (RCM-B) Connector - C310B

Circuit	Pin
HS_CAN_YAW+ (HS CAN YAW +) - VCA23	15(BLUE/WHITE)
HS_CAN_YAW- (HS CAN YAW-) - VCA24	16(GREEN/ORANGE)

Anti-Lock Brake System (ABS) Module Connector - C135

Circuit	Pin
HS_CAN_YAW+ (HS CAN YAW +) - VCA23	60(BLUE/WHITE)
HS_CAN_YAW- (HS CAN YAW-) - VCA24	59(GREEN/ORANGE)