Mk2 Courtesy Lights Flash When Driving But Not Door Open Light!

[Caff]

When driving along the courtesy lights occasionally flash and I can hear the click of relays. This is getting much worse. The "door open" light on the dash does not come on though. Have replaced three door switches but am wondering if this is not the problem as because the "door open" light not flashing implies the problem is elsewhere. This is driving me nuts, I've turned all the lights out but the rear ones for the tail gate can't be turned off, so they flash (annoying at night) and the clicking  can't be right. The courtesy lights all work as normal when doors are open.

Any ideas of where to look.

[chromedome]

Check the wiring between the door pillar and door on all doors. Common place for broken wires.

[Caff]

I'll have a look but I'm wondering if the problem is deeper. It doesn't think any door is open. Hence me thinking the switches might be innocent. There's some sort of control for turning the lights off when the ignition is on or when the doors have been shut for a couple of minutes. I'm wondering if this is the area of problem - but what to look at? Car electrics are not my thing!! :(

[BrianH]

Check the wiring between the door pillar and door on all doors. Common place for broken wires.

Starting with the boot door if i were you

 

Your looking for broken or bare wires inside the gaiters (the rubber boots in the hinge section of the doors) info on splicing new sections in in the faqs (don't just rejoin them as they were already short and this will only make them shorter and even more likly to break again)

[sparky Paul]

Agree with the other posters above, almost all of these weird problems with lights, locking or electric windows can be traced to wiring faults in the door gaiters.

 

As above, start with the tailgate door, then driver's door, then check the others.

[gregers]

also look at the door switches in case theres a bad earth within them.

[Caff]

Having thoroughly inspected the wires on the tailgate, and rebound a few, this problem continues. It comes and goes. We've had a good look at all the wires and think we've caught all the ones that had insulation breakdown/cracking. The wires themselves were all still in good condition as far as was visible and are now well bound up and immobilised.

This is beyond annoying and is less intermittent, the lights are on nearly all the time and the problem seems to be aggravated with forward/backward motion. Switching off the engine means I can't raise the passenger electric window as the computer thinks a door is open. Could it be an earth failing?

Could this be a relay? Do I have to start replacing door switches again, is there a particular set of wires (colours) which I should be having an ever closer look at? Every so often the problem goes away and I think its solved. I've been running back and forth to the tip so all the doors are being opened and shut (and slammed) repeatedly, 

It's so distracting to drive with this problem! I'm no electrician and am struggling with this.

[Caff]

Is the controller under the passenger seat anything to do with courtesy lights? An interesting thought is that when I pull the ignition keys out but have the lights on the "computer" knows whether the driver's door is open or shut.

Edited July 29, 2014 by Caff

[SilverBeast]

Have you only checked the tailgate? The wires  i  the gaitors to the doors suffer the same issue, start with the drivers as this gets most stress (more than hatch as you use the drivers door every time you drive the car).

 

There is also an bundle of earth wires (brown I think) that are under the plastic trim on the sill that runs under the passenger door. These aren't joined particularly well and are prone to failure by corrosion if the rear wash pipe joint in the same trim has ever come apart and leaked.  Search the Forum for details of this.

 

Failures in these door/hatch gaitors and this earth joint have been reported to cause lots of different issues.  To fault find you could disconnect the door gaitors and see if that stops the lights flashing (you will need to reconnect them again in order to be able to use the central locking or do it the old fashioned way with your hands and the key). I believe there will also be a connector in the boot to allow you to disconnect the boot wiring.   That should be inside the panel where the jack etc is stored.

 

Just taping up the wires won't fix most issues:-

(i) There will be broken/failing insulators inside cracked wires inside the insulation which can cause high resistance (and heating) and voltage drops.

(ii) Immobilising the wires will make the bundle more rigid and apply more stress to the "outside" wires leading them to breakdown/fail sooner.

 

Unfortunately the only way to repair them reasonably permanently is to replace the section of wire that is in the gaitor so the join is inside the door where it doesn't get stressed so much.Easy to say, not so easy to do and fortunately I haven't had to do mine yet.

[Caff]

Thanks for your reply SilverBeast. Having fiddled with all the wiring the lights are flashing constantly and it's difficult to say which area of fiddling has aggravated!! I shall have to give it another go. I'm not sure the doors shut with the door gaiters disconnected. If I do have success I will post it here. It would be so much easier to know which wires could be the culprit amongst the bundles.

[BrianH]

The front seems more likly to fail particually the drivers as you use it more often! Your best to pull the gaiter off each and have a thourough look on all of them - the only one i found on mine intact was the front passenger door. Trouble is the door and boot wires cause all sorts of random symptoms - mine for example not only effected the locking (expected) and the rear screen heater (also expected) and the windows but also the radio would lose its memory every time ignition was switched off despite it appearing to have the required 12v on the correct feed (i guess it was momenterally dropping the voltage when ignition was switched off).

 

The hatch also suffers quite badly for two reasons - it opens further than the doors (its got around 90 degrees of movement in normal use) and it also has a lot of wires going into it making it more prone to problems.

 

As stated above the only way to be sure they are fixed is replacing the damaged section keeping all your joins out of the hinged area. You run the risk of the deadlocking activiating and being unable to open the door if it breaks at the wrong time as a couple of people have discovered recently.

[seanwhu]

I had exactly the same problem and turned out to be the door switch for the interior lights.  It had lost its rubber cover and whenever I went over a bump all the interior lights would flash without the door open sign on the dash.

 

Not sure if the thickness of the rubber cover would have caused it but a new switch resolved everything.

 

Like everyone else has said I would also check the wires one by one as you will find some breaking or broken.

 

Good luck

[Caff]

I took off the driver's side rear interior panel and the tailgate panel to free up all the wires for the tail gate. We checked each one and found a few more with lightly damaged sheathing. None were broken at all and none worn. There were no problems with any other door's wiring and earthing for the tail gate is in that area below the fuel tank filler. So we went back to the switches - again: there must be two circuits, one to turn the dash warning light on and one to turn on the lights when the doors are open. 

My original diagnosis was correct and the new replacement switch I had bought( to replace the one I had crushed) was faulty and getting worse. Because the problem initially was intermittent I had began to think the problem was elsewhere. So four switches (we changed others "just in case") and many hours later all is working correctly. 

As a final gesture the fuse also blew. I think it was no 63, a mini fuse on the "vertical set" which took me a while to find going through them one by one!

So all is quiet and not clicking again. Thanks all for your help, as ever.