brake light trubles

[mogatron]

Hi team just put a new wing on rear left side and connected the lights up. now there's a problem. the brake lights work until the head lights are turned on then. when you push brake with lights on it turns all the lights off except a small glow from filament. anyone any ideas why? mot's awaiting on it.
Cheers ben.

[bmcecosse]

First off - disconnect the wires to that light - does the problem go away ?? If yes - reconnect one wire at a time and keep trying. It most probably is an earthing problem - so check the light is properly earthed to the car body.

[mogatron]

ok is the black wire the earth one? also does it made a difference if its a fiberglass wing?

[PSL184]

Yes, black is earth. With a Fibreglass wing you will have to run a separate earth to a metal part of the body as the light cannot earth through the fibreglass.

edit to correct spilling mistak

[bmcecosse]

Ahhhhhh - now he tells us! Fibre wing

[mogatron]

arr ok so do i need to runn a wire from the lighting cluster to the body then? or does the black wire do that. think the black wire is earth to the bumper mount already.

[mogatron]

woops only ment to say that once

[bmcecosse]

That's ok - I had a triple post earlier too! The black should be earth - obviously in your case - it isn't!