BMW 125 PT-CAN Bus Wiring Problem Caused By Short To Earth
This BMW 125 was brought in to GP Motor Works after a couple of other workshops failed to find the root cause of the problem. The issue was the car wouldn’t crank or start at all. It should also be noted that the vehicle arrived at our workshop in the stripped-down condition as shown in the photos.
As you can imagine, this was a particularly difficult issue to solve as BMW’s wiring systems are complex and several bus wiring networks transmit messages to more than one system. The vehicle’s data exchange of the control units is across various bus systems each with completely different features. These bus systems are also interconnected via gateways that interchange data between the connected bus systems.
Effectively, we had to disconnect every single bus system, one-by-one, to isolate which one’s worked and the one that didn’t work. It turned out one of the wires in the PT-CAN bus was shorting out to earth which prevented the car from starting.
We repaired the damaged wiring and the engine started successfully. Mission accomplished!
We returned the car to the original workshop so that they could undertake the task of refitting and restoring the interior.
Please don’t hesitate to us for help for any electronic or electrical problems.