dimmer wire tap location for defi gauge

[crimson180sx]

I have a couple of Defi Racer gauges and there is a wire for dimmer so that when the headlights come on the gauges dim for night driving. Can anybody tell me the wire I should tap to have them dim when the headlights turn on?

Thanks

1991 240SX Hatch

[themadscientist]

There is a wire that goes to your stereo you can use. Look for a wire that gets voltage when you turn the lights on.