Wire spliced into rear light?? C5 tourer

[wheeler]

That box is screaming out aftermarket parking sensor control box.
One connector for each sensor, one for the power & one to the beeper.

[WickedElf82]

I must try to see if I can turn it down and see if that works then would be one mystery solved, still need to fix my brake/indicator lights though

[WickedElf82]

Ok as suspected the extra box in the boot is for parking sensors etc so one mystery solved, still no luck with my light cluster, would it be a faulty ground wire?

[mickthemaverick]

Re the brake light connection. Have you proved it is definitely the brake light wire which has been tapped into? If so could it have been to power a high level brakelight if the original feed had gone faulty?

[WickedElf82]

I can confirm it is indeed the brake light that it is tapped onto as the black wire in the original picture has been soldered onto the yellow/green wire of the brake light cluster just before the block that goes into the light

[mickthemaverick]

Then I would say that either it was a feed for an auxiliary brake light, maybe a bicycle rack or similar at some point or being used as a sensing wire for a long lost driver aid? The other thing you can try is disconnect it and see if anything else stops working!!

[WickedElf82]

We have already discovered that the black wire that is spliced into the braking lighting is from the other loom that had black box attached which has been an aftermarket reversing sensor. I’m trying to suss out why my brake/indicator cluster aren’t functioning, I thought it was because of this wire but it seems nothing to do with it. If I move the wires about inside the connectot block that goes into back of brake light the brake light just about comes on and goes off again, the indicator never functions

[mickthemaverick]

In that case I wonder if you have a faulty lamp base which someone tried to cure by running an earth from the parking sensor unit but that will not help if the fault is in the actual unit strapping. Try taking out the offside unit and seeing if it will work with the nearside wiring plugged in. If so then you know you have a faulty unit and need to replace the unit. Other than that it means a proper fault tracing job with a multimeter. Good luck !

[WickedElf82]

I don’t think that will work as the plug only goes in one way and the cables would be the wrong way round if I swap them round if that makes sense?

[mickthemaverick]

It makes sense but I'm not sure it is right. Although the light units are obviously sided I doubt the plugs are. Certainly on my c4 both units had the same plugs so worth a look!