here is the connections for the car head unit 1995 camaro:
1995 Chevrolet Camaro Stereo Wiring Information
Constant 12V+ Orange
Switched 12V+ Yellow
Ground Black
Illumination Gray
Dimmer Brown
when we replace the head unit we will have an extra: Dimmer Brown , Illumination Gray
so how can we use this cables like adding :Illuminated Cigarette Lighter LK-2240 products, buy Illuminated Cigarette Lighter LK-2240 products from alibaba.com
or interior light!
what is the difference between the 2 cables? aren't both positive?

 

the grey wire is on or off. the brown wire is controled by the dimmer wheel as to how many amps are allowed to go into the wire. does the head have a dimmer wire?

 

so If I wana connect a simple bulb?
connect both to the 2 terminals of the bulb?
where can I have the ground?

 

no only one would go to the bulb wire, then run a ground to the other. depending on if you want the bulb to dim with the dash bulbs or if you want it to just come on like the dome light. if you want bulb to come on with headlights/parking lights and dim with the dash lights you would want to use the brown wire and a ground. if you just want the bulb to come on with the headlights/parking lights then use the grey wire and a ground.