After searching through some posts and some web hunting, I'm still a little leery of hooking up the Illumination Wire (IW) for a new head unit. This is on a 3rd Gen Taco, but may apply elsewhere I suspect. I'm replacing an older Alpine (no IW) with a new Alpine 9845.
I think I have it narrowed down using this procedure found at the 'Talk Audio' forums here:
Using a Multimeter to Solve Headunit Wiring Hell
5) Probe each of the loom/connectors using the red multimeter probe until you find a reading of around 12V. This is your permanent live wire. Label it using the pen and tape.
6) Turn on the ignition (set it to the "Acc"/"Accessory" position.. there's no need to start the engine. Probe all of the pins/wires except the one already identified as permanent live. When you find one with around 12V, label this up as the "ignition switched live"
7) Turn on your headlights, and repeat the process from step 6, ignoring already identified wires/pins. When you find a 12V signal, label this as your "illumination" wire (basically it tells the headunit to dim the display when your headlights are on).
So here's the factory plugs, plus a plug that I think was added later in an install.
The upper two plugs are the factory wiring, and I’m thinking the lower single wire plug (white/green stripe….had to Photoshop the green stripe in the photo to show properly) is something someone added the previous install.
Many of the places on the net show the Toyota factory wiring using a solid green wire for illumination. See:
This is clearly not the case in my ’96 Taco.
The 12V ‘lights on’ wire is definitely green/red stripe. The thing that has me puzzled is the extra single plug wire that goes to 1.77V only when the lights are turned on. The white/green stripe wire on the single wire plug comes out of the harness and is then finds it’s way to the small white factory plug in the ‘O’ position of that plug.
The 'O' position shows 'DO NOT USE' in the above diagram, but....???
I’m thinking I should hook up the Illumination wire from the alpine to the 1.77V first….and see if that works. If that doesn't work, I may try the 12V green/redstrip wire that goes to the large blue factory plug at the 'J' position. (Also shown as 'DO NOT USE').
Mostly I’m just not up to blowing fuses with this thing at this time. I’ve seen some threads where people have run into problems with the IW, so thought I’d check to see if anyone successfully done the IW and where they connected it to.
Sorry so long winded…..