No Communication With Chassis Control Modules After Reconnecting Battery (SSM70378)

NO COMMUNICATION WITH CHASSIS CONTROL MODULES AFTER RECONNECTING BATTERY

TECHNICAL SERVICE BULLETIN

SERVICE INFORMATION

Symptom 304000 Suspension System

ISSUE

If the battery supply to the vehicle is disconnected for any reason (for example, removal of transit relay at PDI), the Chassis Control Module (also known as 'Air Suspension Module', 'Suspension Module', Integrated Suspension Control Module', CHCM on SDD) may not power-up correctly. As a result, the SDD service tool will report no communication with the CHCM module in several session screens (see below). This will only affect a small percentage of parts and on an intermittent basis.

The vehicle may also display error messages on the cluster relating to suspension and adaptive dynamics faults:

• "SUSPENSION FAULT Max Speed 30 MPH"
• "Adaptive Dynamics Fault"

The SDD tool may also log the following DTCs from modules which communicate with the CHCM:

XF X250 Sportbrake, XJ X351 

Content

Modules which receive CAN messages from the CHCM module may log the following DTC

• U012A-00 (C12A-00)  - Lost Communication with Chassis Control Module "A"-no sub type information 

CAUSE

The power up strategy currently in place for the CHCM and CHCMB can cause this concern

ACTION

To resolve the issue, fully disconnect the negative lead from the battery terminal. Wait for 5 minutes and re-connect the battery negative. Repeat this process if necessary. Ensure that a power supply unit is NOT connected to the vehicle when doing this.  SDD should confirm communication with the CHCM and CHCMB (note: the CHCMB is optional) and cluster error messages will no longer appear.