An interesting case was referred to us recently. A Rover 75 Diesel with numerous electrical faults, namely an ABS light on, DSC light on, Speedo inop, tachometer inop, temp gauge inop and auto transmission emergency programme activated.
We started with a global ECU test using our DEC Super-scan Diagnostics tool. Test results revealed no communication with the ABS and instrument cluster and C.A.N faults in PCM and transmission module.
The next step was to carry out C.A.N Bus analysis which highlighted voltage out of range CAN high. At this point further checks were required to determine the cause. Considering the age of the vehicle, the customer was contacted and informed of the process to date. Having given his permission to proceed further, we began further checks. A physical measurement of voltage in the CAN BUS revealed a very high voltage in the dominant circuit, bearing in mind the lack of speedometer, ABS light on and no communication with ABS this was the logical place to start.
As the module is difficult to access we took the decision to remove it's voltage supply (remove fuse) and re-check CAN voltage, which was then found to be normal.
At this point we decided to access the ABS module and investigate. Upon removal of the battery, battery tray, fuel pump etc. the full horror was revealed (see photo on the right). The module and harness was severely attacked by acid probably from a previous battery failure / charging fault.
The customer decided to supply a used module and part harness from a donor vehicle. We fitted the module and harness which immediately cured the faults. Just one final thing was to check all related modules were functioning correctly and configure the variant coding on the ABS module which came from a vehicle without DSC (our was fitted with DSC). Final road test, job done!