PSM

Fault code 1550

Reverse gear signal

NOTE: The 'reverse gear signal' is sent as a digital signal via the CAN data bus from the vehicle electrical system control unit to the 'gateway control unit' and 'PSM control unit'.

Diagnostic conditions
- Ignition on
- Internal function test on PSM control unit
- Shift into reverse gear and out again.

Possible causes of fault
The 'reversing light switch' electric circuit may have one of the following faults:
- Fuse 43 in right fuse carrier faulty (electrical fault in electric circuit)
- Short circuit to B+ (electrical fault in electric circuit)
- Short circuit to ground (electrical fault in electric circuit)
- Open circuit (electrical fault in electric circuit)

Affected pins
PSM control unit connector:
- Pin 15 'CAN drive (low)'
- Pin 11 'CAN drive (high)'

Vehicle electrical system control unit, connector [A]:
- Pin 20 to 'reversing light switch pin A1'

Diagnosis/troubleshooting