No brake lights, pls help :/

Hey guys,

I've done a bunch of searching, but haven't found anything quite the same as the problems I had yesterday.

Connected my trailer up as I normally do, tested lighting, all good. Woke up next morning, went to use indicators and nothing. Not even working on the Discovery. I guess due to a wiring fault on the trailer, its knocked out the Discovery's lighting?

Pulled over, found Indicator/brake light 15a fuse blown, replaced it and indicators worked again on both Discovery & trailer.

But still no brake lights Disconnected trailer, still no brake lights. Everything else working as it should, just no brake lights at all.

Everywhere I've searched point to brake light switch, but I doubt I'd be that as everything was working spot on before? Is there a brake light relay? Or some other fuse I could have blown?

Please help asap! I'm doing a 800 mile round trip in a few days, need this fixed!

Thanks!!

PS- she's a 1996 300tdi 7 seater

No relay and as the indicators are functioning proves the fuse is okay.
Unless u suspect a wiring fault the only places to check are the brake switch, has it an in and output of 12v, and the trailer socket isn't shorting out the brake light circuit in some way which is the easiest, so start with looking at that.

discool said:

No relay and as the indicators are functioning proves the fuse is okay.
Unless u suspect a wiring fault the only places to check are the brake switch, has it an in and output of 12v, and the trailer socket isn't shorting out the brake light circuit in some way which is the easiest, so start with looking at that.

Click to expand...

Thanks for the reply!

Ok cool, I will check both. I'm sure the trailer was to fault which knocked out everything, but its strange now the fuse has been replaced, yet brake lights are still not working.

Hopefully its not a huge job to find the fault!

I had similar when I connected my trailer up and tested it just before setting off on holiday. It was the brake light switch just above the brake pedal. It was dirty, just needed cleaning,it took all of 30 seconds.

As above, brake light switch fault. Something must have blown the fuse. 2 min job to change!!

Well, done some investigating this evening and indeed, it seems the brake light switch is to fault. Mine is an ABS model, so I have the brake light switch with the plug & 4 wires going into it.

If I unplug the brake light switch & bridge the 2 green wires together using a small piece of spare wire, the brake lights work!

Strange that the switch has randomly failed. Guess I'll buy another, and hopefully that'll be that Quite a quick fix, hopefully!

I have yet to re-connect the trailer though! But that's another story

The extra load of the trailer lights may have been enough to burn out the connections in the switch if it was on it's last legs anyway.

markSX said:

The extra load of the trailer lights may have been enough to burn out the connections in the switch if it was on it's last legs anyway.

Click to expand...

You might be correct on that.

Just to update - all fixed Brake light switch arrived this morning, took all of about 20 seconds to refit.

Very glad it was a simple fix!

Good stuff, although mine is an abs model and when my brake light switch went, stuck in a new one to find lights still not working, and needed it plugged into the computer to have the fault reset before the lights came back on