illumination wire pioneer avh-p4400bh? Please Help

My 3200BT dims correctly when headlights on. Unable to currently pull it out and tell you which wires are there and connected, but it works for me.

 

Did you get a chance to pull the stereo and check those wires?

 

The pioneer harness should only have 1 single solid orange wire on the back of the radio... if it has 2 (1 orange and 1 orange/white), STOP and read the manual to determine which is which. If its solid orange, it should dim the radio when +12v is applied to it. To get this +12v DO NOT TRUST OR RELY ON THE ORANGE OR ORANGE/WHITE WIRE on the harness that connects your pioneer harness to your OEM plug. You need to test the actual OEM wires 1 at a time. Turn your light switch to off... then put the black (-) side of your multi meter to ground and the red (+) to 1 of the OEM wires. Once your multi meter is in position, turn the light switch to parking lights only (first click) this SHOULD dim ALL of your dash lighting (guages, AC, etc) Once you turn the parking lights on, check your multi meter reading... you need to find the wire that is nothing (0 volts or -ground) when the lights or OFF, then switches to +12v when the parking lights are flipped on. Only ONE wire should do this. Leave the key in the ON position for the entire time your testing. Just look for the wire that changes from nothing to voltage when the lights are on/off. If the wire is 12v with lights off, then nothing or ground with lights on, its the WRONG WIRE. keep searching. Hope this helps. Let me know if I can describe this better for you.

 

This, pretty sure it even has a sticker from the factory stating what it is.

 

Mine is backward, whet I turn the headlights on the HU gets brighter...???? Pioneer x2800