Head unit dimmer?

[minicooper172]

I've got a crummy Alpine head unit in my Zimmer at the moment, and I want to change it to my Sony one.

I did it before using an ISO adapter, but it made the dash lights go all funny. It made the clock lights come on even though I had no lights on. Is this because of the orange wire, "dimmer"? What the hell does it do? My Sony head unit doesn't have this function... What should I do?

[mrLEE30]

the dimmer function is not available on all head units, it is basically an input that goes to 12V when the lights are turned on, in some higher end head units it is a variable signal input from 0 to 12V to reflect where the dimmer knob is set thus dimming the head unit accordingly.

i have always chosen to wire the complete stereo in myself rather then relying on adaptors where you do not test each wire giving you issues likt you describe normally due to cowboys being in there before you.

standard stereo end of the BMW loom should be

green/red - permanant live
Purple/white - switched live with ignition
Brown - ground
red/white - signal from lights on for headunit dimmer if fitted (this goes to 12V when the lights are switched on)
White (not connected to the above loom) is the signal to lift/lower the electric ariel

speakers blue/black and blue/brown are right rear
yel/black and yel/brown are left rear
blue/red and blue/black are front right
yel/red and yel/black are left front

and you can see all these wire below (ignore the blue wires on the left they are my amp signal cables)

if you dont want to use it then simply find the wire, cut it and tape up the end.

[minicooper172]

Thanks for that, in the end I just took the pin out and put it into a blank slot, and now it all works, woo!