I've done a search, and although there are many threads about the airbag warning light, there was nothing similar to my problem...
I swapped out the seats on my 156 on the weekend. It all went well, except when I came to swap out the passenger seat.
The new seats have side airbags, which my old ones did not. Not a problem on the drivers seat - there was no existing wiring on the old seat, so I dropped the new one in and left the side airbag loom just hiding under the seat.
The OLD passenger seat, when I came to remove it, had a wire leading from somewhere inside the seat body to a two core cable, one white wire, one yellow wire, wrapped in a yellow sheath going under the carpet. There was no connector on this, it was soldered in place and wrapped with insulation tape. It looks like someone has tampered with it before.
The NEW passenger seat has three wires leading from inside the seat body to a yellow connector block. I assumed this was for the airbag, as it was identical to the one on the driver's seat.
When I took the old seat out, I just cut the two wires, thinking I'd get the seat in, reconnect the battery and see what happens. The airbag light is now on all the time!
The wiring I've left unterminated must be something to do with the airbag - but I don't understand how. The old passenger seat didn't have a side airbag, so why would part of the airbag wiring loom go into the seat body? Is this wiring compatible in any way to the airbag wiring on the new seat - can I connect to two of the wires on the new connector block?
Can anyone help?