No interior lights working

[AlexP]

Hello.

I recently purchased a 2021 Polo Match Evo AW. It is an ex hire car and came with a single key fob.

I noticed that none of the interior lights are working in either the cabin or the boot. No lights come on when I unlock the doors, open the doors or press any of the interior light switches. This includes both the vanity mirror lights.

The bulb holders I prised out do contain live bulbs with intact filaments.

I checked electrical continuity across all fuses in the engine bay and under the steering wheel - all good. I then found a fuse diagram which suggests the interior lights do not even have fuse protection anyway?!

I then bought a VCDS Hex-V2 cable. The VCDS scan suggested "Supply voltage for interior lights - Short to Ground". Does this point to a Body Control Module issue?

Another thought is that interior lighting has been deliberately disabled? Is there a way I can check this using VCDS and re-activate it? As a novice I am reluctant to dig too deeply into VCDS in case I end up bricking a module.

Thanks for any help! Cheers.

[alexperkins]

As I recall, there is a fuse for this. Whilst it goes via the BCM, it is still fused

[AlexP]

Thanks. I have just re-tested all eight BCM-related fuses under the steering wheel (plus one in the engine bay) and they are all good.

I have purchased a used BCM for £31 and will (attempt to!) code it with VCDS and swap it out.

[iichel]

Save yourself the effort, with VCDS you can't do it.

[alexperkins]

Is this one an ODIS/VCP job?

[iichel]

odis online yes. cp, key matching

[alexperkins]

Ahhh. Did wonder if it had CP

[AlexP]

Okay, thanks. I was not aware of component protection. My other cars are much older and don't have these modern annoyances.

I am visiting VW in the next week or two to have a new key supplied and activated so I will mention the interior lights and see if they can do anything. No doubt they will insist on supplying a brand new BCM if that is indeed the issue.

[RUM4MO]

You should try using a proper Indie VAG workshop, they will have all the necessary licenses and will not treat you and your used BCM like a bad smell.

[AlexP]

You should try using a proper Indie VAG workshop, they will have all the necessary licenses and will not treat you and your used BCM like a bad smell.

Agreed, I have someone in mind. They have looked after my Touareg and Golf for the last 15 years but I stopped using them this year. I may give them another chance.

[AlexP]

Finally had the new key coded at VW yesterday.

Their systems did not provide any more detail about the lack of interior lights and they went down the "book the car in for further investigation" route.

My independent VAG guy has confirmed he can de-CP and code my eBay BCM so I am going down that route as the next step. Hope it's a simple as that, I don't want to go down the route of pulling the car interior / wiring looms apart.

[AlexP]

Some progress...

My independent guy pulled out the front left sun visor (a sod of a job in itself, apparently) and found this pinched wiring which was causing the short. It could well have been badly installed at the factory. The sun visor remains unplugged and I will find an eBay replacement.

Interior lights then started working but when I re-started the car after paying there were no lights...

VCDS was plugged in and he ran an Output Test which got the lights working again until I got home and switched the engine off. Now the lights don't work again.

I wonder if the system is unhappy that the connector to the sun visor mirror slide switch is unplugged?

EDIT: Or could the short have damaged the BCM?

Polo vanity light switch.jpg (644.38 KiB) Viewed 5502 times