I had a slight issue whilst getting the tracking done last weekend. My local garage said there was a bang, puff of smoke then it wouldn't start......
After pulling the dash, I could see the melted switch wires.
I ordered a new switch as I could start the 90 (not putting the details on an open forum) so I knew it was not the starter etc.
Anyway, after fitting the new switch today, still nothing. I removed the glow plug wire and she started first turn of the key.
This is what I found
I replaced the loom and all is well
The glow plug nearest the timing belt had shorted to the air box (my fault, I had put it back on around 5mm out of position).
It's a 200tdi conversion and the air filter is mounted at the front. All fixed, after putting it in the correct position I added some heat shrink to ensure no accidental shorting!