I installed a 2012 CT200h steering wheel ($60 for the wheel + $180 for the airbag from Ebay) and sort of figured out the wiring. It's much easier to re-pin the connectors going into the button circuit than to re-pin the black 12 pin connecter going into the clock spring.
We'll be using cruise control dial and connector, black 12pin connector to clock spring and all the wires from gx470, and black 7 pin connector (left hand buttons) and white 8 pin connector (right hand buttons) from CT200h.
1. disassemble both steering wheels and disconnect plugs, swap the cruise control dial from gx470 to ct200h (2 screws, this part might be unnecessary as both dials seem to have same part# but I did it anyway).
2. Examine the white 8 pin connector going into gx470 button circuit:
| Pin# | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| color | yellow | green | black | grey | white-red | white | brown | N/A |
| func | ?? | ?? | ECC | AU2 | ILL+ | EAU | AU1 | N/A |
De-pin all the wires by using a small flat head screw driver to lift the tiny tabs, cut open the black sleeve as we will be splitting wires into 2 directions
3. Examine the black 7 pin connector going into CT200h left hand button circuit:
| Pin# | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| color | red | red-white | brown | white | grey | grey-black | white-red |
| func | IL+2 | IL+2 | AU1 | EAU | AU2 | AU2 | EAU |
The Red-white, Grey-Black and White-red wires all go into the 8 pin white connector, leave them alone
Re-pin the following using wires from gx470 harness (use flat head screw driver to push the tabs down a little before inserting to make sure pins lock into place):
| gx470 wire | white-red | brown | white | grey |
| ct200 connector | red | brown | white | grey |
4. Examine the white 8 pin connector going into CT200h right hand button circuit:
(I've omitted the wires coming from 7 pin black connector)
| color | yellow | white-black | green | pink | white-green |
| func | +DP | -DP | DIST | ECC1 | ECC2 |
Depin the white-green (ECC used by cruise control dial from ct200h, since we're using gx470 dial we have no use for this) re-pin the rest with wires from gx470 harness:
| gx470 wire | yellow | green | black |
| ct200h connector | yellow | green | pink |
Notes:
Info are from notes and memory. Apologize for lack of photos as I was rushing.
I still don't know what the yellow and green wires are for in gx470, but I matched them to ct200h anyway.
My 2004 doesn't have wire for -DP, so I simply de-pinned the white-black wire.
After putting everything back together, the left hand buttons work and illuminate. The right hand buttons won't illuminate due to the fact that they need a -DP wire to complete the circuit (shown below in ct200h diagram):
(maybe connecting W-B to White(EAU) would work as that's how left side is lit up, or connecting W-B to ECC as -DP and ECC both seem to be ground anyway). But since my old 04 steering wheel doesn't have those buttons to begin with I didn't bother. The newer model gx with more buttons should have -DP. Theoretically the right hand buttons should also work because the circuit is complete. But I may have to reprogram the AXXESS steering wheel control adapter and configure the Sony head unit to make use of them.
Disclaimer:
Do it at your own risk, use this as a reference but not necessarily the truth. I don't take responsibility for any issues after the modification
Happy modding!
