This is a weird one.

With the ignition off my lights work fine but as soon as I turn th eignition on the headlights switch off (but the side lights still work).

I have utilized the original Sierra wiring loom and fuse/relay box (from a 1990 1.8 Sierra) along with the original Sierra column indicator stalk (which as you know also operates the main beam). I have fitted a different light switch on the dash facia. It’s a standard rocker OFF/ON/ON switch that switches side and main beam and appears to work fine without the ignition on.

With the ignition off, I thougt the Sierra would only allow side and flash main beam but I get the reverse when I turn on/off the ignition.

Any ideas?

Also, is it legal to have headlights working with the engine off. Why does the Sierra turn the headlights off when the ignition is switched off?

Does the switch you fitted earth the light relay same as the column switch when it is used. There is also a wire that carries the earth from one side of the column switch to the other which I think will need to be connected betwen the sidelight and headlight circuit. It's alright if lights work with the ignition off but if they go off with ignition it saves battery if you forget.

[Edited on 13/8/04 by Peteff]

Sounds like you have the relay for the headlights connected wrong.

The sidelights run on a totally seperate circuit on the Sierra - no relay.

Follow the Wiring Diagram (Haynes) as I did and it should function correctly.

Ah yes I see the problem Pettff. The Sierra light switch supplies +12v to side lights but grounds the main beam which is not compatible with my light switch.

I'll take another look at the circuit diagram and see what I can do.

Thanks guys,
Roger

Solved this one. What I did was add an additional relay into the headlamp switch circuit so that when the headlamp is switched on via my custom switch, the original headlamp wire is grounded. It all works fine now.