Brake lights not working.

[FinalD]

My check control unit keeps telling me that I have brake light problems, I've been ignoring it as the car isn't on the road yet so it doesn't matter. Now though I'm trying to get it ready for an MOT so it is time to fix it.

Pressed the brake pedal and not a single bit of light came from the back. Changed bulbs for some that shouldn't be knackered (brand new) and I get the same result, no light when braking and the check control tells me one (or all) have failed.

All the other rear lights work (fog, reverse, indicate, driving light) so I'm confused as to just why the brake ones aren't working.

I realise this means there is likely a break in the circuit somewhere but I'm thinking that you lot will know if there are any common failure areas.

Any ideas from you knowledgeable folk?

[Grrrmachine]

The silliest thing is normally that the brake switch has come loose from its mount above the pedal. Some wiggling might be all that's needed.

[Brianmoooore]

I take it the LED comes on with the ignition and stays on all the time, since the E30 arrangement requires the brakes to be used before it can test the circuit.
First of all, check fuse #6. If that's OK, chances are the brake light switch (top end of the brake pedal) has failed, often as a result of a brake pull rod that's long overdue for adjustment.
Pull the two wires off of the switch and link the wires together with a short piece of bare wire.
Turn the ignition on and the brake lamps should light.

[capri_rob]

I've had to replace a couple of brake light switches in the past - common failure.

[FinalD]

It's f'king cold outside so I can't be arsed to go back out into the garage tonight, but I shall have a look tomorrow/sat. As far as I'm aware, all of my fuses are fine as they are something I keep checking quite often if something electrical doesn't work.

The light does indeed stay on so I guess it is the switch on the pedal. I'll stick my head in there tomorrow or sat. I take it that if I replace the switch I need to adjust the pull rod too? I saw mention of it in the wiki but was unsure as to quite what it was going on about.

[Brianmoooore]

The light does indeed stay on so I guess it is the switch on the pedal. I'll stick my head in there tomorrow or sat. I take it that if I replace the switch I need to adjust the pull rod too? I saw mention of it in the wiki but was unsure as to quite what it was going on about.

The tests I've suggested may be just the first two of many! No guarantees it's the switch at this stage, but until I know the results of these I can't advise further.
Whether your pull rod needs adjusting or not depends entirely as to whether it's out of adjustment, which is yet to be determined.

[FinalD]

Tested the switch, as a switch, it does work, pull it out and the lights come on, push it in and they go off. However, there appears to be no spring action to force the switch out of the unit so it is always set to 'off' and the pressing of the brake pedal doesn't change this.

I guess this is time for a new switch.