boost gauge light wire.

[sleepy2lazy]

Hey guys,
This is an Autometer 20/20 boost gauge in my 95 gsx.
I have always had it work, but never hooked up the lighting aspect of it properly.
Also installed is an A/F blinking gauge. The red wire and the black wire is spliced with the A/F gauge wires.
Currently 1 is hooked up to one of the wires in my cigarrette lighter wires. The other also hooked up to one of the cigarrette lighter wires.
Now here's the problem, the Boost Gauge Light is always on. Never off when driving. Doesn't come on / off with my headlights, its just always on.

I was wondering, which cigarrette lighter wires do you hook up the boost gauge light wire in order to get it to light on and off ?
and if so, which wire?