Nightmare With Reverse lights Not working - Cant find the problem

[Vdubster]

HI all im hoping some one can help as I have exhausted myself with this one.

Basically My reverse lights have stopped working, after the conversion it appears and after my last mot ( only recently realised they wasn't working with failing its new mot )

1 - No power at rear reverse lights ( using led lights all round and all others work perfect, literally only reverse lights )
2 - No power at Green connection under passenger seats ( which im glad as this hopefully means I didnt or haven't trapped a wire in the back )
3 - fuse 10 is it? that works fine and double checked ( fuse box in front of battery ) so power to the fuse and power from this point onwards
4 - no knuckles later and some serious bending through the engine I managed to disconnect the connector from the reverse light switch on the gearbox/engine, tried to short it with it in reverse ignition off and on, lights on and off, got absolutely nothing reverse light wise.... couldn't quite get to the electrical switch with the volt meter to test so in not sure if there is power there or not.
5 - put the switch on a new reverse switch I bought, pressed the button in, absolutely nothing, so I feel its not a faulty reverse switch...althought cannot be 100% sure.
6 - it seems I have no power in between the reverse ignition switch and the from what my crap understanding of electrics is the j519 onboard supply unit? im sure I've eliminated everything else.
7 - I've come to the conclusion its either a trapped wired or bent pin between the reverse switch and the j519 unit or the j519 onboard unit its self? would I be correct in these assumptions?

The only strange thing about this is that about 6 months ago my rear van doors went crazy constantly beeping, vw installed a new wire for this, I get the funny feeling that new wire starts and comes from the same place I think my reverse light wire does the j519 onboard supply unit which im lead to believe is around the driver lower dash area? have they knocked a pin or cable or etc? or im I completely wrong on this? im a complete novice and its taken hours of reading to get this far, any input advice or expertise would be be really appreciated at this point.

This has caused me more hassle than the entire first time van conversion! I have no idea if there is anything obvious or incorrect I am or aren't doing. thanks again!

 

[Pauly]

Start with the basics
Get a scan of the van and see if theres any faults
Sometimes if the van detects an error it can shut something down and wont start it again until the error is cleared

Have you tried a battery disconnect to allow the van to reboot ?

 

[Salty Spuds]

I’m assuming, and please correct me if I’m wrong, that the reversing lights aren’t actually switched by the gearbox switch. I assume that they are canbus, & the switch in the gearbox sends a signal to the Central electrics module to tell the module to operate the lights. If all this is true, it might not be as simple as a 12V circuit via the gearbox switch. It may be 5V. If you plug it into VCDS, you should be able to force the lights to come on regardless of the gearbox position. This will let you start eliminating possible causes.
Or I might be talking bolllix.

 

[Pauly]

Make sense to me, vcds will be able to do an output test and manually activate the reverse lights, you will also be able to see if the input trigger is reading

 

[mmi]

3 - fuse 10 is it? that works fine and double checked ( fuse box in front of battery )

No, it's fuse SB15 (10A) - at end of centre row - for manual transmission only.

 

[CAL VW T6]

Hi All
I have a similar problem with my 2019 T6 camper conversion.
Firstly I noticed the reversing lights would come on then go out? Thought this was an earth leakage issue - BTW there are two on my vehicle.
Yes it has a pop top, awning, Towbar (with full VW electrical kit fitted).
When I connected the caravan the Reversing lights on the caravan work fine!
Whilst in for Cam Belt and water pump I asked them to look at the reversing lights for me (add £125 diagnostics to the bill)
It also had a major service at 4 years old (only done 30k miles) - it has an "All" In plan on it.
Anyway collected with no MOT (due 9th March) as not done so it didn't fail and still no Reversing lights - explanation of "a broken wire between the B pillar and the light clusters - reason caused by the convertors"!
I spoke to the suppliers they said must be the awning fitters or Towbar - of course.
Previous trip to the Towbars fitters no problems there.
Trip to the awning fitters - no obvious issues there either.
Trip to supplier they said unable to give opinion but would contact auto electrician - poss 3 weeks wait. MOT Due 9th March?
So I set about trying to find this broken wire.
LED roof lights out, front passenger seat out (nightmare this is), felt through LED holes (really sharp edges) to cable and removed B Pillar plastics, both light clusters out.
Found light green plugs and Black / Green wire - Continuity TICK Ok - jiggled wiring loom best I could no change.
Painstakingly threaded new wire from N/S D Pillar up across and down B Pillar. Tried to bypass wiring loom - no good! Idea was to cut and loin new wire to back of light cluster and then ru a link to the O/S cluster and do the same.
Checked the tow-bar 13 pin electrics and everything working except the reversing light pin 8?
Checked for a signal from the body control panel to the green connector - NO SIGNAL - Ah now this is different as I had a signal albeit briefly before it went I to VW???
FINDINGS - no signal from the BCP!
Spoke to tech at VW said it should be showing up as a fault which `I could reset. - this did not show and did not work. They said it could be the reversing switch - however this again was fully functional before the VW visit.
So totally at a loss I have taken into VW today for them to solve - I hope it is simply reset the BCP system, they have a spare wire now if they insist the original loom is damaged, then rebuild my seats etc... and MOT the vehicle.
I will of course update you with whatever solution we find.
I have not had much choice but to return to VW as I need the camper next week as it is my main vehicle and I use for trips to London / Scotland working.

I have researched on here, lots of helpful information etc..., but unfortunately no solution found.

Thanks for listening!

 

[CAL VW T6]

Hi All
I have a similar problem with my 2019 T6 camper conversion.
Firstly I noticed the reversing lights would come on then go out? Thought this was an earth leakage issue - BTW there are two on my vehicle.
Yes it has a pop top, awning, Towbar (with full VW electrical kit fitted).
When I connected the caravan the Reversing lights on the caravan work fine!
Whilst in for Cam Belt and water pump I asked them to look at the reversing lights for me (add £125 diagnostics to the bill)
It also had a major service at 4 years old (only done 30k miles) - it has an "All" In plan on it.
Anyway collected with no MOT (due 9th March) as not done so it didn't fail and still no Reversing lights - explanation of "a broken wire between the B pillar and the light clusters - reason caused by the convertors"!
I spoke to the suppliers they said must be the awning fitters or Towbar - of course.
Previous trip to the Towbars fitters no problems there.
Trip to the awning fitters - no obvious issues there either.
Trip to supplier they said unable to give opinion but would contact auto electrician - poss 3 weeks wait. MOT Due 9th March?
So I set about trying to find this broken wire.
LED roof lights out, front passenger seat out (nightmare this is), felt through LED holes (really sharp edges) to cable and removed B Pillar plastics, both light clusters out.
Found light green plugs and Black / Green wire - Continuity TICK Ok - jiggled wiring loom best I could no change.
Painstakingly threaded new wire from N/S D Pillar up across and down B Pillar. Tried to bypass wiring loom - no good! Idea was to cut and loin new wire to back of light cluster and then ru a link to the O/S cluster and do the same.
Checked the tow-bar 13 pin electrics and everything working except the reversing light pin 8?
Checked for a signal from the body control panel to the green connector - NO SIGNAL - Ah now this is different as I had a signal albeit briefly before it went I to VW???
FINDINGS - no signal from the BCP!
Spoke to tech at VW said it should be showing up as a fault which `I could reset. - this did not show and did not work. They said it could be the reversing switch - however this again was fully functional before the VW visit.
So totally at a loss I have taken into VW today for them to solve - I hope it is simply reset the BCP system, they have a spare wire now if they insist the original loom is damaged, then rebuild my seats etc... and MOT the vehicle.
I will of course update you with whatever solution we find.
I have not had much choice but to return to VW as I need the camper next week as it is my main vehicle and I use for trips to London / Scotland working.

I have researched on here, lots of helpful information etc..., but unfortunately no solution found.

Thanks for listening!

Okay so finally fixed woo hoo
VW had it for 12 days - luckily they were not working on it for that length of time!
It would appear I had dislodged the problem wire so it was not longer shorting out? This doesn't explain the lack of signal though.
Anyway they found the signal issue and rebuilt the seats etc... and lo and behold the reversing lights now work. I maintain they had disabled the fault on the system.
Still the bill was only £130 as I had done all the prep work etc... We have left the spare wire in just in case.
So we are all up and running again with no absolute answer other than be vigilant when you are screwing and or drilling into the channel between the "B" Pillar and the "D" Pillar. The whole rear loom passes through here and is clipped to the structure.
Shorten the screws and take care.
Thanks

 

[DXX]

So we are all up and running again with no absolute answer other than be vigilant when you are screwing and or drilling into the channel between the "B" Pillar and the "D" Pillar.

Seems to be a common problem.