Driver door lock mechanism replacement

If your driver's door lock mechanism fails, and this usually caused by corrosion of the internal micro-switches, then you are likely to experience several typical symptoms;

  1. The security alarm starts going off erratically when armed.
  2. The interior lights stay on, or come back on some time after locking.
  3. The passenger door tends to relock after opening the car using the key fob.
When opening up the door panel to examine my lock mechanism, the lock and electrical cables were wet, with visible corrosion on the connector pins. I later dismantled the whole lock and the corrosion had extended into the internal micro-switches.

The easiest solution is to replace the complete lock, but others have stripped them down and then only replaced the micro-switches themselves. Unfortunately, if your car is an early model then you will find that the design of the replacement lock has changed.

Click to enlarge The old lock looks like this

Click to enlarge The Rover part number for the new lock is FQJ102262PMA. Cost as of Feb 2002 61.78 inc VAT.
Be aware that others have been given a different one (part number FQJ00080PMA). You can tell if you have the right part by stripping off the door panel, ensuring that the door lock thinks it is closed by pushing a pin into the catch (as though you had closed the door), and attaching the 6-wire connector and pressing the blipper. If you have the correct part then the mechanism will lock/unlock. If you have the wrong part then nothing happens.

The new lock differs in, at least, two important ways.

  1. The connectors are different - they are now on flying leads rather than part of the mechanism. Also the smaller connector is different to the old one, so you will need two new connector parts and need to reuse the actual metal connector pins and cable from the original connector.

    Click to enlarge Click to enlarge Click to enlarge Part No's are YPC10069 and AFU3791. These are, respectively, a very small bit of yellow plastic, which inserts into the connector once you've fitted the pins and wires, and a black plastic connector hood.

  2. The bar that goes to the door lock is has an extra 90 degree twist at the end, presumably to ensure that it cannot become detached.
To fit the new connector, you will have to cut open the old connector to retrieve the metal pins and wire. Using a Stanley knife, make a slit along the length of the side of the old connector being careful not the cut the wire! Ease out the metal connectors, which are attached to the end of the wires, and the soft rubber bungs.

To help to line the pins up correctly, plug the new adapter into the new catch mechanism and push the totally black wire (car) into the connector where it will mate with the black wire from the catch. Now do the same for the other (black/orange?) wire to the grey wire. If you now plug the big connector in the interior light should come on! - Push something in the catch and the light will go off. Try some other operations. Only now strip the old lock out out of the door.

Disconnect the wires and fit the lock using the screws. Then connect the key lock to the catch - the thin metal bar should snap into the plastic clip on the back of the lock. Ensure that the key can be turned to lock and unlock the door.

The metal bar that comes from the original door handle can be reused. Push the green plastic clip off the bar and pull the bar out from the hole (look at the new mechanism first). Repeat this on the new mechanism as well, and transfer the old metal bar to the new lock.

Pre MK2 circuit diagram
Dieter's site with a Pre MK2 assy drawing halfway down the page

Thanks also to Will Munns, Cambridgeshire, United Kingdom, who suffered from the same problem.