I took the car out at the weekend, travelling in convoy. At one of the rest stops, I was told that my brake lights were not working properly. I asked someone to jump in the drivers seat and pump the pedal and bingo, brake lights come on and off - they are working I says to myself.

When I get home I decide to investigate a little further. I put the side lights on , and the brake lights stay on constantly, and the lights do not go on/off when the brakes are used. so it must have been a bit disconcerting for the people behind me seeing my brake lights burnging into their eyes in the early morning dark.

I decide to turn the side lights off, and then pump the break pedal - bingo the side lights and brake lights come on in reponse to the brake pedal.

I take the key out, and pump the brake pedal and the whole ignition side goes live (except the fuel pump).

I hate electrics with a passion. can someone give me some ideas of where to start?

Cheers
Craig

[Edited on 7/2/11 by aka Keith]

Yellow Pages under auto electrican

sounds like a bad earth on the stop tail lights, when the lights are on they are earthing through the stop lamps.

are your stop lamps fed via the ignition switch, or direct from battery?

Hi keith, long time no blat!

once its a bit warmer i would be happy to give you a hand looking over it but i would say its probably your stop / tail lights shorting together ~(sommon if water gets in them)

turn lights on (so brake lights come on) and remove stop tail bulb on one side, if brake lights go out its your problem, if not try the other side.

You have a back feed from Non Ign to Ign live circuits, probably in the stop tail bulb holder.
Is the bulb in correctly ?
Is the earth good ? if not it will back feed until it finds an eath path

Hope this helps


& dont forget to report back what it was !

RD

either a single contact bulb in a twin contact holder or one of the bulbs has an internal short to bothe contacts (filaments arced together)

Thanks folks, you have given me somewhere to start. I was just about to plan ripping the loom out.

As soon as I get some garage time, I will try and report back.

Cheers
Craig

As already said Bad Earth in one of the rear lights --- easy to diagnose as it is very common fault

"either a single contact bulb in a twin contact holder or one of the bulbs has an internal short to bothe contacts (filaments arced together) "

I would strongly agree with the above statement, highly unlikely to be anything like a bad earth or any of the other weird & wonderful suggestions - it's a dead simple one this, the 2 circuits are joine & I'd bet a £ to a penny it will be a bulb problem as above!