help installing autometer tach in 73 challenger

[charger2fast4u]

i have a autometer tach i am installing in my 73 challenger. i have a question on the dimmer switch hook up to control the brightness of the tach. the plug on the back of my dimmer switch in the car has 5 wires comming off of it and is a 3 prong connector. the colors of the wires are 2 black wires with white stripes on them 1 brown wire and 2 yellow wires. which wire will i splice into to control the tachs lighting?

[John_Kunkel]

The brown (actually tan) wire is the one you want.

[charger2fast4u]

alright so i would splice into the middle connector on the plug which is the single tan wire? just turned brown from age and the current.