This issue seems to come up every other week in the MK4 section and because I have some pictures from when I fixed mine, thought I`d do a
guide.
Usual disclaimer: This is for information only, I accept no responsibility if you hurt yourself/someone else/your car/ someone else's car/your wallet/any animals etc.
Ok then, Symptoms of a failed microswitch are:
"Lights on" buzzer not working when you open the driver`s door (after leaving lights on).
And the car locks itself 30 seconds after unlocking, EVEN if you opened the door.
There are threads on cracked soldered joints on VW forums (same symptoms) but it seems just as common that the button that operates the microswitch wears down to the point where it`s not doing anything.
This button is only plastic and everytime you open the door a metal cam rubs over it to push it down, so eventually it wears away and stops working. This was the fault on mine and I managed to fix it without any expense (although it took me the best part of a day to do).
The main part of it is that you need to remove both the plastic outer and metal inner door cards.
So, this is how you get access to the door lock module:
Start by prising the door handle apart as in the pic, the upper part comes away upward and the handle just pulls off toward you, remove the plug under the window switches.
There are two philips screws concealed in the handle that need to be removed (see pic2).
You don`t need to remove the chrome handle above it but there is a plug behind it you take off later.
Remove the torx screws at the bottom of the door card.
Remove the plastic clips (8 I think) holding the door card on by pulling the card outwards toward you - they will pop out.
The card is sealed in tight to the window seal so hit it upward from the bottom until it comes away at the top.
Once it is free remove the handle cable, the led and mirror plug from the back.
Now for the metal door card:
Plug the window switch back in and open the two black rubber bungs, lower the window until you see the two bolts on the window brackets like this:
Remove both 10mm bolts and tape the window in place with STRONG tape and protect your paint at the top of the door by using a rag. You could remove the glass later but why complicate? Remove the window switch again.
Remove the plugs for the speakers, window motor and led if you have one. The wires will just hang there.
Remove the 11 bolts holding the card on and it should pull away - there is a seal on it.
Remove the plug for the lock module.
Unclip the card from the lock module by pulling it forward (towards the door hinges).
This is easier if you have a facelift car as they don`t have door pins; if your`s does, just be careful you don`t bend it too much at this stage.
Refitting is pretty much reversal of removal but I will say make sure the window engages into its two brackets properly or it could really ruin your day.
Once the metal card is off you can remove the lock module which is tucked away in the corner of the door, only 2 screws for it but they are 12-point star drive so careful you don`t round them using something else!
At this point it`s personal choice - swap it with a new module or try to fix yours.
This is mine while still fitted (sorry I did`nt take any pics of the actual job once removed!).
You can (hopefully) see the white button under the cam, what I did was prise the microswitch off the module and take it apart, then took the button out and turned it 180 degrees, and refitted everything.
The button wears down at an angle, so by turning it round it gives the cam a fresh profile to push on... it should last for a bit anyway!
New modules are expensive, but you could try a second-hand module off ebay, I`ve seen them for about £30, make sure it`s off a newer car though, as there should be more material left on the button... if you had a newer button AND turned it round it should last even longer.
Oh, and test your fix BEFORE you fully re-fit the door cards... just in case you need to get in there again!
Hope this helps someone anyway!
Cheers,
Neil.