Need To Know Power Wire

[NcTurnL]

Hey guys
im hooking up my after market temp gauge on the E30

I have my ground and sensor wire set up but where can I tap in to a switched ignition power wire?!?!?!?!!?
I was thinking a wire from the ignition switch ( where keys goes in) so when it turns to acces, or run, the gauge will start working, but which color wire is it!!!!!
I need to know asap, because tis getting dark here!!!!

Thanks you ahead of time!
-Jon

[AndrewBird]

I'm not sure of the color, but use a test light and figure it out. Should take <2 min.

[NcTurnL]

I dont have a test light ( stupid me ) But I do have a multimeter!
What do I do, just check each wire when I have it turned to run and see which one has power?