I took a day off work today because Ian Haynes kindly volunteered a day of his time to look at the central locking issues. It took hours of methodical testing to work out that the locking system had four separate faults:

• Intermittent 12v power to the control unit
• Knackered control unit input stage
• Passenger door lock motor fails to give unlock signal to rest of car
• I’d missed a little part of the driver’s door lock rebuild, which meant the deadlock didn’t work

We managed to rebuild the lock with a spare part quite quickly. Equally, once we’d established the dodgy connector causing the intermittent power, that was easily resolved. We’ve tested the system with Ian’s control unit and it runs perfectly. However, obtaining a new control unit and passenger lock mechanism proved harder, with a local scrap yard giving us the run around before eventually yielding a unit that didn’t work – fortunately we tested before paying.

Ian and I are going to spend the next week or so trying to source known good second hand items; BMW are asking over £100 for a new control unit. Ian also sorted out the door open/closed switches so the car now turns on the interior lights and allows electric windows and sunroof control when either door is open – little things like this make the car seem so much less of an old knacker.

While Ian was beavering away I noticed some rust on the sunroof tray edge. I’ll have to dig out the anti-rust tools from my transit days soon I think…