For some reason out of the blue my Peugeot 306 developed a fault on the central locking, As soon as I locked the doors, they would pop open again, either by key, remote or pushing the door lock down inside the car. The first thing I did was to nip out and buy a new control unit, only to find that my control unit was working perfectly.
I then turned my attention to the door locking units themselves only to find that they are working fine. I then realised that somewhere on the system I have a broken wire or wires, that made the central locking unit think that one of the doors was not properly shut. So I got out my electric kit and started to find a way to make the system work while I tried to find the problem, and this is what I came up with.
Step 1: Locate the central locking unit
on my 1997 model the central locking unit is under the back seat on the driver’s side, if you pull the bottom seat up and move the carpet you will see the wires going into it. Now drop the back part of the seat down, lift the carpet and you will see 3 black screws. Undo these and the unit will pull out from the housing.
STEP 2: You will see two connectors attached to the unit, sometimes it’s one black and one white, but it can be different, disconnect the two connectors just to be safe. On the black connector take a close look at the wires and you will see a numbered code on them; you need to locate the wire M623 yellow and green. And 6291 a white wire at the other end.
STEP 3: Connect a wire between these two wires M623 Yellow and Green and 6291 a white wire, as long as you have the same numbers I have stated then you will be ok as colours may vary. Once you have connected the wire to these two wires plug both connectors back in. And then try the central locking. If your connection is good then the central locking should work again.
What you have done is called shorting the circuit, the central locking system works on a loop, and somewhere on the loop you have a bad contact such as a broken wire. Connecting the wire to the two wires makes the system believe that the circuit is made and all doors are shut, basically you have closed the circuit.
Now you have your central locking back, and if you want you can take your time trying to find the pesky broken wire/wires. Or you can leave it as it is. It’s up to you. I hope this has helped you out like it has me. I hope it works for you like it has for me. All the best Colin