I noticed that on the HU rear speaker out connector (R3 ) besides the left and right pair of wires there is a 5 wire (to connector pin 5) which is white/green.

It's not documented in any service manual diagram I searched so far.

As you all are aware, all Toyota (since 1991) and Scion radios have only 4 wires on this socket to the rear speakers but now I found this 5th wire on mine.

Has somebody any idea what's for ?

 

Yeah I noticed that too on wire harness when I was installing my amp. According to shis PDF it shouldnt even be there. http://www.installdr.com/Harnesses/Toyota-Wiring.pdf

My guess is that must have something to do with the steering wheel controls since thats something new they added for the 06's. I was thinking to measure it with a multimeter but in the end I decide not to mess with it. let me know if you ever find out, I would like to know what it does also.

 

my 06 has it with no steering controls, the guys at the dealerships don't know what its there for, neither did the guys at the stereo shop, it could be for the head unit they put in the rs3.0

 

If I recall, the green/white wire is the illumination wire to the head unit.

 

Cool, that opens up some new possiblities for some light mods :D

 

Be Carefull !!!!!!!!!!!!

This wire has nothing to do with HU illumination !!!!!

Toyota specs for HU illumination has been allways on pin 10 of the main R2 connector which powers the unit and provides output to the front speakers !!!

 

So far it has nothing to do with the steering wheel controls, this wires are located in R9 (20 pin) connector.

I did some fast tests (unfortunately didn´t have time to hook a scope) and noticed around 2 DC volts when the HU unit is on.

Perhaps it has something to do with the optional subwoofer so If some body has the optional subwoofer and could check how it´s hooked to the vehicle it could help. The sub is mono so it need combined signal from both channels, and it should be sourced before the front / rear fader. Since the sub is selfpowered it only needs ground, constant battery, acc +12 v and the signal: in short 4 wires if signal ground is common with the vehicle ground.

Original Sub wiring is also not documented.

 

https://www.scionlife.com/forums/viewtopic.php?t=20742

Please see the above link for more information. I'm no expert but it does state the green wire is for the HU Illumination. I also have the Pioneer TS-DRC1BB speakers in my xB and the instructions instruct me to hook up the lighting to the speakers to this wire. Now, I did hook up the speakers a different way rather then the instructions told me so I can't say for sure this wire is really for the HU Illumination. Only pointing out what the tech section shows for this wire.

 

One thing I learned after many years of dealing with car electrical and diagrams is to never blindly trust colors, specially with Toyota and now with Scion.

If you cross check HU wiring color between XA and TC for example, some of them are not the same.

For example XA uses black and yellow for rear left and red and white for rear right but TC uses Brown and yellow for left and red and white for rear right. All going to the same pin number on the HU rear connector.

By the way if you check my first post it says white/green which is traslated as a white cable with a green continuous strip. You noted a green /white which of course is not the same !!!!