Faulty rear tail lights help please brake light fault

[aarc]

Hi all I’m diagnosing the several faults with my e30 now tackling the rear tail lights on start up it pops up with a fault brake light once the brake switch is depressed it’s fine as per normal when I have my main beams on indicating or in reverse my reverse bulbs keep blowing, so that’s why have only one bulb for reverse however when it’s in revere or main lights are on the entire left tail light lights up? And I have no reason as of why the bulbs seem correct, there’s no obvious corrosion in the lights or connectors? Could this be a faulty earth? If so where would this be located?

[Speedtouch]

Check the lamps check unit and its connections, which I gather is located to one side of the boot, behind the trim.

Sounds like one of the lamp earths could be faulty, or possibly a dual-filament (brake light) bulb is fitted instead of a single filament type, so all the bulbs end up earthing through each other.

Are you using the correct voltage and wattage bulbs in the reverse lights?

[aarc]

Thank you for the response I highly doubt it’s a bulb as I’ve replaced all of them and they are single filament I can confirm that. I have a tourer where approximately as in what side would this light control check unit be?? Would it towards the rear wheel wells or would it involve me stripping the side panels more?? Thank u in advance

[Speedtouch]

These threads may be of interest:
https://www.bimmerforums.com/forum/show ... ght-solved

https://www.r3vlimited.com/board/showth ... p?t=269494

On a saloon, it is on the left side of the boot, near the radio aerial but I'm not sure if this applies to the Touring.

[Stefan on probation]

Is there a loom on the touring that goes in to the tailgate?

[ChrisHC]

Before tackling the bulb check unit, run a temporary earth from the metal casing of the rear light unit to a good earthing point and see if that makes a difference.

[aarc]

Hi guys ive checked the Light control module and all the points and soldered a few points still have an issue, now thinking that its most definitely a earth fault, can anyone indicate to me exactly where the earth point for the rear tail lights are located on the tourings please?? cannot seem to find them in and rear boot hatch?

[ChrisHC]

You can confirm whether or not it is an earth fault by running a temporary supplementary earth from the casing of both lamp units to a good earth somewhere. You could use jump leads perhaps.

"........on start up it pops up with a fault brake light once the brake switch is depressed it’s fine as per normal" That is a little ambiguous, but to avoid doubt that is how it is supposed to work.

[Brianmoooore]

From your OP, you definitely have an earthing fault, and there is no possible fault, other than an obscure alternator one, which could possibly blow reverse light bulb, and in this case, reverse light bulbs would be the least of your worries.
Lamp check module for the rear end is located inside the LH luggage compartment door, tucked up behind a bit of body coloured metal. Earthing point for the entire rear of the vehicle is right at the front of this compartment, where all the brown wires converge.

[ChrisHC]

Could someone have given you 6 volt reversing lamp bulbs?

[aarc]

Ok excellent guys thank you so much will firstly see if its a faulty contact at the earth point need to strip part of the boot interior now, if I still have no luck I shall run new earth lines, thank you so much for this guys