Switch location question - Boot Lid?

[Andrew L]

Hi,

I currently have two minor niggles on my 08 reg CC, both appear to be related to boot lid micro-switch(es?).

1. Boot interior light goes off (or very dim) when boot lid is fully open, comes on fully when boot is only partially opened.
2. Left reversing light sometimes flashes on and off when vehicle is parked with ignition off!! (and not in revers gear) The right hand one functions normally.

The reversing light problem is the more worrying, sometimes it illuminates fully when the ignition is on, and no, the car is not in reverse gear. It appears that this can be cleared most times by opening and closing the boot lid, but not always. The reversing lights are of course on the boot lid. Recently I had to resort to un-plugging the affected light cluster to stop it shining a white light at the rear whilst driving.

I have looked behind the liners on both sides of the boot compartment but I have so far failed to find a switch or switches. Am I missing something obvious? I did find a whole bunch of connectors for the boot lid wiring on the left side, but if there was a micro-switch I failed to spot it.

Can anyone tell me where the micro-switch(es) are located please?

Thanks!!

[simonsheil]

I think the micro switch is part of the boot catch.

I had a problem on mine were the fog lights stopped working. It was fixed under warranty, however, as far as I know the problem was the wires into the boot lid has worn through. They are a tiny bit short and get s stretched every time the boot is opened.

[Andrew L]

Thanks, I was coming around to the conclusion that it must all be in the lid. I'll take a look. Thanks again.
Andrew


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[srisport]

I think the micro switch is part of the boot catch.

I had a problem on mine were the fog lights stopped working. It was fixed under warranty, however, as far as I know the problem was the wires into the boot lid has worn through. They are a tiny bit short and get stretched every time the boot is opened.

You are correct,

I had a very similar problem with my boot light not working, after further investigation i came across this shocking conclusion:



As you can see, after un-ravelling the cable tape which manufacturers commonly use to group cables together i came across several cables which had been partially cut into! and one which was comletely cut (boot light) there was no obvious sign of wear and tear from the outside!

I believe that this will be your issue as it would be very easy for all them cables to short together! a very common issue apparently!

to find the location: remove passenger side boot side trim, this is where the boot wiring harness comes out the boot truss - through a plastic bracket (this is the cause!) and then on to several plugs

Hope this helps.

Regards.

[Andrew L]

Thanks very much for the detailed response. I will take a closer look at the area of the wiring you suggest and report back.


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[Hein H]

Hi

Thanks for the info you posted. I had exactly the same issue (intermittent car boot light issues and rear tail light faults) and decided to investigate. I subsequently made a very similar discovery:

VW CC boot light cables.jpg

It was wrapped up with the original VW insulation; removed this and found two cables completely sheared off. There was also no obvious sign of wear and tear from the outside. But this was definitely the issue. Soldered the cables together and everything is working fine now.

I recently had a tow-bar (after-market) fitted and, during routine servicing, asked VW to investigate this issue. They immediately pointed to the "after-market" tow-bar and referred me back to the installer, claiming this as the 'obvious' reason for the issues I was experiencing. Needless to say this was not the case; however, I ended up saving myself a lot of cash by sorting this out myself.

Thanks again!
Regards.

[Andrew L]

I finally got fed up enough of the varying 'rear end' electrical issues to pull the boot interior apart and follow up on the advice from this thread (thank you!), and sure enough, no signs of damage to the external wrap, but a collection of severed and almost-severed brown wires was indeed concealed within the wrapping up near the connectors on the LH rear wheel arch.2014-09-06 14.02.17.jpg

I repaired them with 'butt crimps' and re-wrapped. It's all working now.

The final straw for me was when I could hear the motor in the boot latch (in the lid) operating as the boot lid reached the top of its travel. Previous symptoms included:

• Flashing Reversing light when the car was parked, locked with ignition off
• Boot interior light going off when boot lid opened
• Various dashboard warnings regarding failed rear lights, which were never the bulbs.
• On two occasions colleagues reported that my car boot was open when the car was parked at work. The first time I dismissed it as forgetfulness on my part, the second time I became suspicious... Luckily it seems only to have ever happened at the office! Just before I got around to repairing it the dashboard suddenly told be that the boot was open whilst travelling along the M25, it clearly wasn't but I still pulled over and checked.

The local VW dealer has just informed me that to replace the loom would cost £243 inclusive. Not surprised as there is a lot of labour involved to get to it. I asked how much the loom would be supply only and was told about £45. They only mentioned it because there were a lot of 'faults' stored in the cars 'computer' (hardly surprising), the car was in for a routine service. I had asked them to run diagnostics as the engine management light was on... another story building there!

I can only guess that this problem is going to become more and more common as these cars reach a certain age. Mine is an early example. How quickly this problem appears will presumably depend on how often the boot is opened and closed since it appears to relate to the bending of the wires, the brown insulation is clearly not as flexible long term as is required to tolerate this kind of frequent bending.

[leewhite1957]

Like many others I too recently had the boot lock not working and on investgation found the same failure in the wiring loom just after the plastic carrier which attached to the hinge bracket. I had 6 out of approximately ten cable fractured and two had broken completely. Clearly to me this is a design fault which causes the movement in the cable to break it. Not good enough VW.
Solder and heat shrink to all repairs then a larger heat shrink over the whole area, (Slid over the cable end after disconnecting the 6 connectors.) and all is well now. If you are unfortunate enough to suffer the same, and you plan to use an electric soldering iron, I suggest you disconnect the loom at these connectors to ensure you remove any risk of the iron damaging the sensitive electroniocs on the car. (Mine is a 2010 CC blue motion0.
Hope this helps and thanks to all for a great forum.

[Andrew L]

Well, time passes. In 2016 I replaced my ‘08 Passat CC with a 2014 CC which at 20 months old had only 50 miles on it. So here we are in 2022 and we are experiencing the random boot openings again. Guess I’ll be going for a grovel in the boot again
Otherwise the car is great and thanks to the pandemic it still has very low mileage for its age


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[Andrew L]

Sure enough… removed LH side boot (trunk) interior trim today to get at the wiring loom. The wires are thinner than the earlier model and the plastic bracket has changed shape…
But I started in-wrapping the loom of eight wires and sure enough, there was the damage to six of the eight wires. None had severed yet, but there was clear opportunity for the various wires to short together. Repaired the damage with butt crimps and lots of PVC electrical tape. Think I’ll order the loom as a spare part if I can and replace it. The repair I’ve done should hold it for a while, but I fear the flexing every time the lid is opened and closed will cause it to fail again in a while.


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