For my 88 BRII I'm in the process of installing an aftermarket radio. The existing wiring harness was a mess, all hacked up for a pre-existing amp and subwoofers. So I've removed the old wiring harness and splicing it directly to the wires from the new head unit. I've got all the speaker wires figured out.

Now I'm having a hard time figuring out the correct power combination. I've got it to work in 2 different scenarios, but both options do not automatically turn the radio off when I turn the car off and remove the key. Also the radio can be turned on with inserting the key.

Setup 1 (works but always on)
Green/Yellow = 12v constant goes to Yellow (memory)
Yellow/Black = 12v accessory goes to Red (accessory)
Orange/Black = ??? goes to Yellow (memory)
Blue/Red = illumination goes to nothing

Setup 2 (works but always on)
Green/Yellow = 12v constant goes to Yellow (memory)
Yellow/Black = 12v accessory goes to Yellow (memory)
Orange/Black = ??? goes to Red (accessory)
Blue/Red = illumination goes to nothing

Setup 3 (doesn't work at all)
Green/Yellow = 12v constant goes to Yellow (memory)
Yellow/Black = 12v accessory goes to Red (accessory)
Orange/Black = ??? goes to Red (accessory)
Blue/Red = illumination goes to nothing


If I remove Orange/Black from any scenario nothing works.


So my question is... What is Orange/Black and why can't I find it listed in any wiring diagrams for 88 BII or 88 Ranger? What other combination can I try to get the radio to turn off when the ignition is off and key is removed?

 

The factory diagrams for my 87 show fuse 11 (hot in run or accy) connects power to the radio on y/bk

 

FWIW, theres no orange/black in the 87 diagrams either

 

I would just use a multimeter and see which wire has voltage at all times, which one only has voltage when ignition is on, etc. It would only take a few minutes.

And I really hope those wire nuts are only temporary. Wire nuts have no place in a vehicle.

 

Blue/Red is always hot 12v.
Yellow/Black is on when the ignition is on 12v.

Orange/Black has a very small voltage of .02v when the vehicle is on.

You would think I could just leave Orange Black out of this configuration and call it a day, but that doesn't see to be the case. I wonder if orange/black could potentially connect to chassis. I haven't tried that yet.

You're right, wire nuts are only there till I figure out which of these wires goes where. I've used Posi-twist on all the wires that I know connect where they're supposed to.

 

So leaving the Orange/Black connected with Green/Yellow on radio memory completely drained my brand new battery in about 2 weeks. Had to jump start the engine this morning.

For now I've capped the Orange/Black but I'm left with a non-functioning radio.

One thing I did notice was the last time I went to put my headlights on the speakers made a pop sound and the radio turned off. This leads me to believe Orange/Black deals with illumination, but I thought that's what Light Blue/Red was used for.

 

Rather than guessing, why not visit InstallDr and get the correct information? 5 minutes there will solve your dilemma. Oh, and make proper splices too