Interior light stay on

Evening everyone,
I've got a bit of a strange problem on my 98 Transit Duetto.
For some strange reason all of the interior lights including the main one above the mirror, the little dome ones on the drivers footwell, passenger footwell and the sliding door are staying on all the time.

I can turn the main one above the mirror off via the switch, but the dome ones are staying on even with the engine running and this is also causing the alarm to keep going off.
The only way to stop them being on is by taking the fuse out, but the alarm still goes off after a while probably because there is a constant live somewhere.

I've checked all of the door switches and they are all working ok.

Anyone else had this problem or have heard of it, it's very annoying.

Cheers.

Mike

It sounds like a short to earth on the wiring to the door switches somewhere. That sort of thing can be a nightmare to troubleshoot, and it really means a systematic approach - sometimes necessitating cutting and rejoining wires in strategic places for testing, though obviously that's to be avoided if poss!

One thing to check, though - do you have an extra switch at the right hand end of the dash that appears to do nothing useful? If so, its original purpose (I think) was as an override to turn the cab lighting on, so it may be worth checking just to make sure nothing has come unshipped on the back of that.

Hi Mojo,
I'll check to see if I have an extra switch tomorrow, I don't think I have, be good if it was something as simple as that!

Had a look today and no I don't have that extra switch, so back to the drawing board for me, guess I'll just have to either spend ages trying to trace where the fault is, or just leave the fuse out for now.
Thanks anyway.
Mike