No Crank BKD diesel engine on a Golf 2004 Mk5

[shabazmo]

I have now done a bit more investigation. From the steering module pin A18, I can detect 12v on cranking which I am sure is line 50 supply. I can also detect 12v on cranking the BCM input Pin G1. The output of the BCM to the starter motor relay is pin A11. There is no continuity between A11 and the relay switch pin 86. So that would assume a broken wire between A11 and the relay. I did however do a voltage check on the output of A11. It was 12v, so that's fine. However when the ign was on only, I read 10.8v. Should I ignore this as a spurious reading.

[shabazmo]

Update as follows. I decided to follow the line 50 current from from the steering control module. Line 50 crank signal from the starter switch is energised via the steering control unit and exits via a red and black wire on pin A18. 12v was measured during cranking on A18. The wire then enters G11 on the power supply control unit or BCM. 12v was measured during cranking. The output of the BCM is on pin A11. 12v was measured. A continuity test was done between A11 and pin 86 of the starter relay and was open circuit. Conclusion, the fault lies in the engine bay fuse box or somewhere in between the box and the BCM. Unless I have got this very wrong.

[Crasher]

The do get water in, taking them out is a bit of a pain, you have to disconnect the BUS bar fuses and lines and then unscrew the Torx headed bolt in the centre and it lifts up and disconnects.