Ok, trying to hook up the 12V power wire for my Autometer tach and I’m
not sure which wire to tap into.
Looking in the FSM (as cryptic as it is), the IGNITION SWITCH harness
(E108), there are 5 wires coming out of it:
There is also two wires going to the IGNTION KEY:
Can someone tell me which wires to tap into so the tach is only on when
ignition is on?
just hook it up to ur stereo, or any wire that only gets power when the car is on does (fuel pump)
Yea, guess I’ll do that. So I hook it up to the IGNITION wire on the
stereo right? Or the BATTERY wire?
you need to hook up to the 12v switched, not 12v constant… so that would be ignition
Well almost ran into some trouble doing this. I didn’t bother to disconnect
negative battery cable before splicing my wires and as I was pulling my
stereo I noticed my legroom light went off. Then I noticed the clock,
chimes, dome light and map lights didn’t work. Turned car on and as
soon as I turned it on the wiper went once. Heh…strange shit.
Turned out I blew my ROOM LIGHT fuse. Replaced it and it works fine.
And yea I spliced it with the ignition +12V so it’s working fine. I’ll post
pics of my ghetto tach setup tomorrow 
Something to consider:
If you are running a lot of devices on switched +12V power (like me) you might do well do run a smaller guage wire into the passanger comparment and use a relay to switch it (switched by cig. lighter). This way you don’t have to worry about overloading that circut (and you can install inline fuses of course to ensure you don’t start any fires)
which colour was the igntion wire?
From the stereo? The red one. Well I spliced it on the harness coming
out of my stereo so the head-unit manual had the colour codes.