I noticed the other day that the indicators aren't flashing when locking the car. I found out that the 'convienience' ECU was the culprit. Found the blighter under the carpet in the passenger footwell (r/h drive, uk car), the circuit board is within a plastic box and contains some electronics including 3 relays.
I suspect one of the relays to be at fault (soldered to circuit board). Found the relays on RS, they seem to be dual coil types, well 2 of them anyway, as the indicators flash on opening my car and don't on locking I am highly suspicious of these 2, which one I don't know.
The cost of buying these relays and soldering them on the PCB is approx. £5 as opposed to £200 for a new convienience board, so guess what I,m gonna do? I'll let you know how I got on soon!

Unless anybody knows of a different cause, let me know

Cheers