Crutchfield supplies an adapter harness with their receivers and it includes the power and speaker connectors, but the OE wiring harness has two additional connectors which I gather are for the various inputs. I would like to identify the function of each of the wires in those two connectors and perhaps be able to tie into the factory wiring for the iPOD and Aux sockets between the front seats.

C1 is for power and front speakers, C2 is the rear speakers, the 20pin is C27, and a yet unidentified harness connector "CXX" is 16pin. There's another receptacle on both standard and upgrade radios, the centermost of five, but I can't identify a mating plug on the XB2 harness. Since I'm pretty certain I only had to diconnect four harness plugs when removing the radio, and I can only see four, I don't think that receptacle is used by our cars. The PAC SWI-JACK identifies three C27 pins :

C27
1 - nc
2 - nc
3 - Purple (vehicle speed "SPD")
4 - nc
5 - nc
6 - Black (steering wheel controls ground "SWG")
7 - White (steering wheel controls input "SW1")
8 - Red (steering wheel controls input "SW2")
9 - nc
10 - nc
<next row>
11 - nc
12 - nc
13 - nc
14 - Gray (auxiliary input ground "AUXG")
15 - White (auxiliary input right "ARI")
16 - Green (auxiliary input shield ground "ASGN")
17 - Black (auxiliary input left "ALI")
18 - nc
19 - Yellow (auxiliary input <I don't know the function> "AUXI")
20 - nc

"CXX"
1 - Red
2 - nc
3 - Green
<gap>
4 - Blue
5 - nc
<next row>
6 - Orange
7 - (black taped pair)
8 - White
9 - Black
10 - Yellow
11 - White
12 - Black
13 - (black taped pair)
14 - Pink
15 - nc
16 - Purple

Can anyone identify the function of any more of these wires?

well 3 of those wires will be for the 3.5 mm jack input on the console.. if you take a 3.5 jack and plug it in.. then meter continuity between the wires and the tip of the 3.5 jack.. then you'll find your 3 wires for the 3.5 jack

id be interested in knowing this also.

+ could someone post a pic of the jack that plugs into the back of the HU so that i could see the color and the order of the wires for the ipot/aux input.

well 3 of those wires will be for the 3.5 mm jack input on the console.. if you take a 3.5 jack and plug it in.. then meter continuity between the wires and the tip of the 3.5 jack.. then you'll find your 3 wires for the 3.5 jack
Yes, a similar approach would probably identify the iPod connections as well. I expect the two sets of pairs are grounds, but it appears I would have to cut open their outer sleeves to see if any colors would be exposed -- I'm in no rush to do that.

If anybody has access to the factory wiring harness information, that would be the perfect solution. At the moment I'm working on head unit selection and speaker sound, but I eventually would like to integrate the iPod and Aux into the OE configuration. I'm expecting to have to pull apart the center console, but maybe not. (Normally I'd have bought the factory service manual -- but some $300 plus for the set is a bit steep :(!)

TrevorS, We had a discussion back in April and I linked this wiring info: http://www.fsu-clan.com/scion/audio/audio%20wiring.pdf

Looking quickly, I thik plug C22 is for the AUX input. I didn't look carefully but hopefully this info can help you out. It would be nice to see somebody able to get the factory iPod adapter to work with an aftermarket head unit. I did not see the iPod wires in any of those diagrams. I have more pdfs downloaded at home maybe I can dig up something else.

ok, here is the back of the the premium HU
http://i155.photobucket.com/albums/s295/swartzautoman/Radio3-1.jpg
the 2 on upper left is C1 and C2
the 2 on upper right is CH1 and C27
and i think the one on lower left is C37
i could be wrong.
C22 only has 5 wires, but i don't see a plug on the back that only has 5 wires.
its been my understanding that the one on the lower left is the AUX/IPUT input but i could be wrong.

i have a 06 that i put the 08 premium HU in to and everything pluged up and worked perfect except the AUX/IPOD stuff.

http://i155.photobucket.com/albums/s295/swartzautoman/Radio1Highlight-1.jpg
06 on the left and 08 on the right, i looks like the only thing that was changed is the lower left plug was flipped around.
all of my strearing wheel controls, speed adjusting valume, everything, it all works perfect except the AUX/IPOD.

TrevorS, We had a discussion back in April and I linked this wiring info: http://www.fsu-clan.com/scion/audio/audio%20wiring.pdf

Looking quickly, I thik plug C22 is for the AUX input. I didn't look carefully but hopefully this info can help you out. It would be nice to see somebody able to get the factory iPod adapter to work with an aftermarket head unit. I did not see the iPod wires in any of those diagrams. I have more pdfs downloaded at home maybe I can dig up something else.
Looking at the harness adapter and your document, I've updated my first post ro reflect C1, C2, and C27 (which matches with my steering wheel controls), but my 16 pin "CXX" remains a mystery. I've recounted the pins and the total is definitely 16 -- and so it can't be the C37 connector suggested earlier!

Yes, it appears the set of pins 14 through 19 on the second row of C27 are the auxiliary input. Pins 6 through 8 are further confirmed as the steering wheel "pad", plus the purple pin 3 is the speed signal. That completes C27, and so the iPod must be on "CXX"!

ok, here is the back of the the premium HU

Yes, it appears I overlooked a wiring harness connector :(! When I pull the HU I've currently trying, I'll add its wiring to my top post.

ok, here is the back of the the premium HU

Yes, it appears I overlooked a wiring harness connector :(! When I pull the HU I've currently trying, I'll add its wiring to my top post.

No, I didn't overlook a wiring harness connector. I've updated my first post to reflect that the xB2 wiring harness does not include a plug for that center connector. It could be for the xB1, or it could be used only during manufacturing and/or test of the radios.

So the only wiring available for the iPod is on my mystery connector "CXX" and it may require a point-to-point continuity test to nail those. Too bad we don't have access to the xB2 wiring diagram :(!

just to make sure there is no confusion the pic i posted of the premium HU is out of a 08 xB2.

just to make sure there is no confusion the pic i posted of the premium HU is out of a 08 xB2.

No confusion at all! My xB2 has only four wiring harness connectors (not including the antenna, of course), and that "center" receptacle is not included. So at this point, I'm ignoring it.

From left to right, on the top, doesn't it go iPod, Aux, Speakers, Power?
I'd guess that the lower connector is for the steering wheel connectors.

Nope! Please read the thread :)!

By the way -- if anyone knows where I can get a mating socket for the 20pin C27 wiring harness plug -- I'd be happy to find out about it! I'd really prefer not to have to cut into or T-Tap the C27 wiring for steering wheel and AUX connections. Any connector sources?

Also, anybody know of any problems associated with extending a headunit USB connection to the console between our front seats? That seems like a more flexible solution than adapting to the OE iPOD wiring.