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I did nothing intentionally. I had disconnected the 3 yellow plugs under the driver's seat , passenger's front seat and the air-bag switch in the glove box whilst removing it. It may be an intermittent bad connection with one of those plugs, but there was nothing obviously wrong. I'd looked at the wires in both front door gaiters. There is no apparent damage to any of the wires, but I'm intending to check for continuity this week-end. I also intend to check the coding of the door controller; it came from the same model, so it should be the same. I don't think that would cause this problem. I'd bought the car when it was about 6 months old from a relative. There'd been no repairs done to it. He had paid Halfords to put in a power cable for (I think) a dash-cam and there'd been some problem with that. There was a later earth fault with a connection behind the dashboard, which had caused the AC control display to stop working and the AC compressor had failed at the same instant, for some reason that I've never worked out. Those were two of the 4 main faults (also an EGR valve & alternator pulley) I've had with the car in 15 odd years.

I should have also mentioned that the faults(s) had been the cause of a drain on the battery, that had wrecked one battery and would drain the replacement in about 2 days. The power drain stopped as soon as I had disconnected the door wiring harness. I'd thought that fault had been caused by defective batteries in the alarm module and had replaced that; the original batteries were 15 years old, so they were long overdue for replacement although they were still going strong.

I'm posting the outcome of this, for the benefit of anyone else with a similar problem. It seems to have been a defective passenger door control module. I got a second-hand one from E-Bay, the seat belt fault light has cleared and most of the faults have gone. I've still got a fault "01332 - Door Control Module; Passenger Side 004 - No Signal/Communication - Intermittent", so maybe a broken conductor in the Canbus wires, or a slightly-less defective door control module. I'm investigating further. Answering my own questions. "Is the door control module an electronic 'black-box' controlling most of the other electrical devices in the door according to the Canbus signals?" It is, but it's attached to the window motor, they're usually sold as a pair. There are about 15 or 20 connections to/from the door control module, but only 2 of those connections go to the motor. "Is there an earth point that might cause such a problem & where is it located ?" One of the two studs under the trim panels at the base of the door pillar. In my case, they weren't discoloured/corroded and there was continuity to earth, so I didn't disturb them. I never did work out how to disconnect the yellow connector, it would probably be obvious if I could see it detached from the door.

Continuing this. The door seemed to unlock when the battery was fully charged. I haven't been using the car much during the lock-down. I have now disconnected all of the door wiring harness (except for 1 yellow plug, see below) to try to find the fault. I had thought that the problem was most likely broken wires inside the rubber gaiter on the door pillar, but there was no visible damage to these wires. It might be a conductor inside the insulation, so I intend to check the continuity. The VCDS also showed up several faults associated with the door; 01332 - Door Control Module; Passenger Side (J387) 004 - No Signal/Communication 01332 - Door Control Module; Passenger Side (J387) 004 - No Signal/Communication - Intermittent Fault Frequency: 9 01218 - Side Airbag Igniter; Passenger Side (N200) 001 - Upper Limit Exceeded - MIL ON Address 52: Door Elect, Pass. Cannot be reached I think that the main suspects now are a defective door control module or possibly a defective earth connection. Is the door control module an electronic 'black-box' controlling most of the other electrical devices in the door according to the Canbus signals? In other words, similar to what I know of as an outstation? Is there an earth point that might cause such a problem & where is it located ? There was a defective earth point that had caused problems with the HVAC control, many years back. Finally, I'm having trouble releasing the yellow plug (crash sensor?) that's found in a 2" diameter hole at the bottom of the door. It seems to have blue plastic latch/lock device on it. Can anyone tell me how to release this? Pull the blue latch towards you or push it away?

No answers at all? The immediate problem seems to have rectified itself. I unlocked the car today, the indicators flashed as normal (they'd stopped doing that), and all the doors unlocked. There's no apparent reason why it would have fixed itself. The front NS window was working again. I hope it stays working long enough for me to find and fix the source of the problem. I'm sure there's an electrical fault, I can't think why else the window would have stopped working.

As above, the front passenger door won't open, the window won't open, the central locking won't lock properly. I can't hear the lock in the door operating when I lock or unlock the car. I'd assume this is the door wiring harness, the power to the door seems to have failed. I had a seat-belt warning light come on a week or two back. I haven't used the car in a few weeks and found this new problem. Can anyone tell me how I open the door to repair the wiring please? I'm a bit unimpressed that an apparent electrical failure like this could lock you into the car, I'd always assumed the internal door lever would always open the doors. I've tried spraying WD-40 in the door gap at the lock thing, to no avail. That seems to be the standard solution for a sticky lock, but this problem appears to be a lock mechanism with no power to actuate it.