I'm just wireing boost gauge in. I'm wireing it in to fog light switch.
There's a ground, + battery , and + battery switch wires. I was told it would be ok to wire both battery supply and switch wire wires to the switch wire on fog light switch. Now I've wired it up but for some reason the head lights are on when the headlight switch is of. And when you turn the head light switch to on the boost gauge goes off. Please help

 

I would return your wiring to its original and wire into your stereo loom.

This has your IGN live earth and Illumination. you wont have any probs after that.

 

same as above

 

Mine's off the fog light switch - very handy for a pillar mounted gauge - and it seems to be fine, so it is possible. There's a wiring diagram available here:

.Mac - iDisk

You want to tap into the wires coming from pins 2 and 4 of the connector block; sounds like you may have tapped the wrong wire

D

 

Sorry scoobymyster, reading more carefully it sounds like you've got a three wire boost gauge rather than a two wire. It sounds like your gauge is expecting a constant live feed off the battery + wire, and then uses the state of the battery switch wire to control the illumination, a bit like a ceiling rose in house lighting.

If so then I'd guess - and its very much a guess - that the battery switch wire would go to pin 2, the earth wire to pin 4, and you then need a permanent live feed for the third wire. Afraid I don't know where you'd pick that up from, I don't think you'd get one from the fog light switch. I can see why you'd try to splice both the + battery and + battery switch wires together into the switch wire. Did you perhaps splice them into the wire from pin 4, and your ground wire into the wire from pin 2? While a two wire set up wouldn't care which was the live feed and which the earth, a three wire set up would. As I said though, I'm afraid I'm guessing now

D