Introduction: Volkswagen Golf MK3 Remote Central Locking Upgrade

After many years and many cars it got to a stage where I know roughly what I want in a car and sometimes its the simple little gadgets that make life a little easier.

I own both a 1994 mk3 and a 2009 mk6 Volkswagen Golf, I got the mk3 Golf when I had a beetle and the improvement of having something like central locking was amazing. Years past and I finally bought a new new golf, the mk6 which had remote central locking even better than before.

Recently I put my mk3 golf back into service and let my girlfriend drive my newer mk6 golf, I have no problem swapping back into one of my old toys, but something I did find annoying was having to stick the key in the door lock and lock it like my 40 year old camper. Its mainly when you have a handful of stuff its far easier to press a button than try and put the key back in the door handle and lock it, by which point you have dropped everything!

From the factory the mk3 golf was available with central locking as an option (I dont think it was standard on all models) and on top of that I think the remote locking was a further option, although I think that was available only on 96> models.

So whats this instructable about? Well I wanted Remote Central Locking, Many guides on the internet didnt cover what I want or I came across one which I think was actually wrong! This little upgrade uses a standard kit available off Ebay.

Step 1: What Will You Need?

The upgrade in this instructable is suitable for mk3 Volkswagen Golfs with pneumatic central locking. The kit I used can be used for electronic style I believe also, however thats not covered in this instructable.

So What we need is a few basic tools and skills:

Soldering (this can be done without soldering using screw terminal blocks if you cant solder)
Use of basic hand tools

Soldering Iron
Wire cutters
Craft knife
Heatshrink (or electrical insulation tap)

Multimeter (optional)

and most importantly a central locking kit a bit like the one pictured

Step 2: Examine the Wiring Diagrams

Its important to look at various wiring diagrams before you start to work on this so you can understand if what your dealing with is the same as what I have described here.

The pictures in this step show the wiring diagram from a Haynes Manual (Chilton in the US?) for the mk3 golf itself, the wiring diagram from my unit sourced from Ebay and then finally I drew up a wiring diagram for myself to work from which shows how to connect the 2.

Now the wiring diagram for golf shows a selection of components, the system consists of a fuse box located under the dash of the car, central locking pump(which contains the pump and controller), door switches and door actuators. The bit we are interested is in the wiring connector from the central locking pump as it contains everything we need.

After looking at the wiring diagram for the golf I decided that the system is a 'positive trigger' as seen on the choice of connections for the remote unit.

I sat down and worked out what should go where as you can see on my final diagram. Some items I have not connected because there are no connections/I have no use for them. They are simply marked as NC

I have wondered about the trunk release, I think it could be used with a solenoid to pop the boot so you dont have to unlock the whole car, my mk6 golf does this. I thought might also be cool as a retrofit in my 72 beetle to pop the front trunk.

Step 3: Find the Central Locking Pump & Get to the Cables!

In the Mk3 Golf as far as I know the central locking pump/module is all located in the same place in any country, its in the boot just below the right hand tail light (looking at the back of the car). As you can see in my pictures its fairly easy to get to, a little rubber strap and the insulation casing falls away allowing you access to the pump.

Pull the pump out of this carefully and you'll have a pipe and a small cable loom.

The connector is pretty difficult to get off the pump and you have to squeeze each side of it and it doesn't come out easy. At this stage leave it in place as we are going to do a trial run before we cut anything from the main loom.

However if you really want to take it off now, I found that to get that connector out I used a small screwdriver to gently pry around the connector upwards and eventually it came up and out!

So lets look at a trial run.

Step 4: Time for a Trial Run!

I included this step as I always think its good to mock things up and test them before you cut any wires.

First Step in my mock up was to decide where to mount the little receiver control box, which I put just behind the foam stuff that lines the edge of the boot, just next to the light. In doing so this meant I could determine how much to shorten which cables by of the loom that comes with the remote box. I separated out the cables that were 'No Connection' as marked on my diagram and bundled them up with the cable tie-up that holds the cables together in the packet, this way I have lengths of cable should I want to add in the future.

I had found that the yellow feed wires to the control box were shorter than most of the rest, so cut the red power wire back to the same length(which was a little after its protection fuse). I then stripped back 1/2" of the insulation and twisted the core of all 3 cables together. I also cut the negative and 2 white lock/unlock wires to the same length, stripping 1/2" off the end of each cable and twisting to tidy up.

Once you have your cables to length with twisted ends, poke the twisted end in the back of the central locking pump connector in the relevant matched colours (as per the wiring diagram).

Now give your key fob a go an see what happens?

Did it lock? Good

Did it unlock? Better!

If it locks and unlocks the wrong way round on your fob then swap the white and white/black lock/unlock signal wires round. While my diagram is the right way round, the first time I did get it the wrong way round.

Neither? then we need to do some fault finding (you might need a friend for this)

Using your multimeter (or your friends/dads/brothers) first of all make sure you have power by testing the connector on the locking pump, the red/white cable is permanent live and the brown is earth, if you put your meter across this you should get 12 volts or so. If you don't then your central locking may never have worked?!

If you have power make sure your unit gets power, when you have the cables pushed into the back of the connector, if you press the buttons on your fob, you may hear the little remote control box click. This is the relays working meaning in the unit works.

Have you got a signal coming back from the door locks? There's a switch inside each of the door lock which operates your central locking pump, its does this by supplying power back to the pump for a moment. So using the meter again connect the black to earth and the red probe to either the green or grey cable. Now get your helper person to put the key in the lock and turn forwards/backwards and hold it in one direction for a moment, getting voltage back? If you are then it maybe you just need to push the wires in the back of the connector a bit more.

Try it again, I threw mine together and it worked fine!

Step 5: Cut and Solder Time!

Ok now we have tested the wiring diagram and happy it works now we can go a stage further and make it permanent.

There are 2 ways to do this, firstly for people who don't have soldering skills you can use the little plastic screw terminal blocks for joining wires(also a good method for testing a second time if you like).The second way is solder and heat shrink which looks neater and slightly more professional.

This is the point where I pulled the plug from both the central locking pump and also from the remote locking module, this way I could wire it up and check it without accidentally shorting something.

I cut about 2" from the central locking pump motor, doing one cable at a time: cut, strip back, heat shrink on, solder, slide the heat shrink over the solder, heat to shrink - done.

As you can see it does look fairly tidy done this way :o)

Step 6: I Still Have 2 Spare Brown Wires, What Do They Do?

These wires should have fuses on and are for the indicators. It flashes like any other car does when you press the fob and by holding the lock button it flashes 3 times to find your car.

Because of the mounting point of this little module I found I had to extend the opposite side wire so it would reach the tail light, I once again soldered and heat shrunk these cables to insulate the live cables meaning now the indicators flash when I press the buttons too.

Step 7: Finish!

And here it is, or not! nicely hidden behind the foam and out of the way!

I tested it plenty of times and it seems to work spot on, with the only odd thing being 1 rear indicator doesnt flash as bright as the rest on unlock, not sure why as it works fine when you go find car!

Things I havent covered:

  • Siren
  • Power windows
  • Trunk Release

Siren: I don't know what this does, it may be part of the alarm arming system or sets off the siren to find the car, I don't have any of that and don't need it so I am afraid I don't know.

Power Windows: I don't have this feature but I know roughly how this works, its designed for people with electric windows, and acts as a short negative supply to activate the auto roll up (my mk6 golf you press and hold for this feature) I only have manual winders on my mk3 so don't need it (I do have an electric sunroof but I'd need some relay module to shut this as you have to hold the key in position till it shuts!)

Trunk Release: I haven't tested how this works yet, but its either a negative or positive supply for a brief second to release your trunk/boot lid, obviously this depends on how your trunk/boot works! I can see that with a small relay kit and a solenoid you may be able to open the boot without opening the rest of the car (yet to be researched).