Peugeot 206 remote locking problem

 One only seems to discover the Achilles heel of a particular model of a second hand car once you've parted with your hard-earned cash.
You know… "I thought everyone knew about the way the Escort cam belt is prone to snapping and letting the valves get bent etc…"

My Rover 820 had an oil leak right at the front corner of the engine block where the head bolts on. It seems that most Rover 820s have this weakness but I didn't find out until I asked a local garage to quote me for a repair. They declined; saying that any repair would be only short-lived.
As oil was leaking at an ever increasing rate the only solution, other than selling the car was to fix it myself.
Once I'd got it apart I then discovered that the fault was due to careless assembly in the factory. As the head is offered up to the block a metal locating pin would graunch the head gasket, weakening it and allowing oil to leak out after a short time. You could see the telltale damage to the old gasket.
I was very careful and the oil leak never did recur.

Now to the Peugeot 206
When the remote key is used the doors all lock with a satisfying clunk then almost immediately unlock with a very disappointing clunk.
Lots of advice is available on the Internet, ranging from fitting a unit from a scrap car or a new unit and also a few obscure comments about adjusting the locking plate or squirting WD40 etc.
Examination of the wiring diagram reveals a clue to the problem.
Here incidentally, I'm describing my car which is the simpler model with two doors and without deadlocking (which uses additional wires).
Within each door is a motorised door lock which has two contact sets. One telling the control box that the door is closed and the second that the door is locked.

Why not simply check what is happening using an electrical test meter? Just check the state of the contacts?

Access to the wiring, alas, is tricky.... however at each door there is a small wiring loom that passes from the car body to the interior of the door. When you open the door fully then prise away the rubber cover you can see a connector. This carries four speaker wires, a ground connection, a couple of wires for lock motor power and two wires for contacts, one for Door Closed and the other for Door Locked.

By measuring the resistance between ground and each of these two contacts one can see if they are working correctly. Resistance between ground and the Door Closed contact should be close to zero ohms (when the door is closed) and that of the Door Locked contact (when the door is locked) the same.

If the door doesn't stay locked you should be able to see the resistance change to a low value before increasing again to something pretty high.

In my car the driver's Door Locked contacts measured as they should. To make things easier to measure the Door Closed contacts one can push the door lock lever into the closed position with a screwdriver rather than actually closing the door. This is actually essential as one needs the door to be open to make the measurements.

On my car, the driver's door wiring at the cable from the car body used a green/yellow ground wire and a pair of orange wires for the two contacts. The passenger door used different colours. The same ground wire colour but a pair of purple wires for the two contacts. Four door cars may use different colours again?
With my car I found that neither of the purple wires went to ground when the door was closed.

As the motorised lock unit is sealed (making investigation and repair quite tricky) the easy solution is to cheat and make the controller think the door is closed, even when it's not.
To do this one merely connects the Door Closed contact to ground. In other words connect the green/yellow wire to either the appropriate purple or appropriate orange wire.

Which wire, as in my car there are two purple and three orange?
Looking at the plug which has three rows of three making nine pins in all, first locate the brown wire. This is the same in each door. Next to this are the two orange or the two purple wires connecting to the motorised lock.
The centre wire is the one for Door Closed.

Connect the centre orange or centre purple wire to the green/yellow wire. You can do this by carefully baring the sleeving for a short distance and connecting the two wires together, either directly by twisting together or, as I did, by using a short length of thin wire. Take care to insulate the bare areas before inserting the cable back through the hole into the car body and refitting the plug etc. Test as you proceed and before you reassemble everything...

If you've done the job correctly the doors should lock with a clunk and the indicators will flash.

Good luck!
Of course you will now have to always make sure the doors are closed before locking and leaving the car, but this is surely better than having to leave the rear hatch unlocked as is the case when the system is not working..
Alternatively you can buy a new motorised lock unit and fit this… or maybe even just kick the door or spray everything liberally with WD40..
Don't forget though, that to diagnose the correct faulty lock motor you will have to go through most of the diagnostic process outlined above…

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