Timm's E31 Rear Lights 5-Minute Emergency Wiring Repair
LICENSE PLATE LIGHT FAIL - REAR FOG LIGHT FAIL - and other BULB FAILURE warnings

It's winter in the UK, MOT next week, it's pouring with rain and there has been thick fog the last couple of days - when I used the rear fogs yesterday I got the REAR FOG LIGHT FAIL message on the OBC. Sure enough when I went around the back to look I had:

This is sure to be due to the failure of one of the BROWN ground wires failing in the loom that runs in the hinge area of the boot (trunk). I've done this repair a couple of years ago and it looks like another of the wires in the loom has failed. I'm not going to attempt the correct repair before the MOT as it's pouring down so I need a quick fix. Here's how:

This combination of missing lights means that I have lost the BROWN wire in the left-hand hinge loom - but we also know that the BROWN wire in the right-hand hinge loom is OK - so what we are going to do it join the BROWN wires together somewhere in the boot (trunk) - and the easiest place to do this is on the licence plate lights.

The tools above are all you need, a long Pozi screwdriver, some equipment wire and a pair of side-cutters. We are not doing any soldering today, we are going to use an age-old technique of squashing wires into connectors!

Undo all four screws on the two licence plate light housings - do this with the boot open and you will not lose the screws. When you replace the lights fit the screws to the housings first - it is so much easier.

Disconnect the connector from the housing and note that one of the wires in the connector is BROWN - that's the one we want on both sides. Next we need to wiggle the new bit of wire between the two apertures

I found the easiest way to do this is to poke it in from the left-hand aperture just below the lock until it pops out at the right-hand aperture - it was easier than expected and only took 10 seconds

Strip about an inch of insulation off using the side-cutters and twiddle it neatly

Poke the end of the stripped wire in the connector that is connected to the BROWN wire

And refit the licence plate light effectively squashing the new wire so that it makes contact - this works well

Do the same on the other side - and then refit both lights making sure you don't squash the wire anywhere

And that's it - all done and ready for the MOT - all rear lights are now working as they should. I will fix the loom when the weather improves but I did this on my last E31 and I forgot all about it for a couple of years! The long-term repair of this fault can be found HERE

All done, time for a cup of tea


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