So I purchased a aftermarket pioneer radio and a SWI-RC pac audio steering wheel switch adapter. Now the radio installed fairly easily, however, the steering wheel switches have been another issue.
According to the adapters install guide, the 'white' wire from the adapter needs to connect to the vehicles grey/red wire. Now, I can't seem to find any red/grey wire.

The adapter company told me to go to the clock spring and check for the wire that has voltage that changes. My concern with that is that I didn't think the steering wheel switches carried any voltage, just some ohms that would change. I don't know, but there has been blood and sweat (figurative and literally) gone into this little upgrade.....

 

Is there a wire on the old harness that changes voltage when you push the buttons? There has to be a wire in the clock spring that runs the volume. Everything electrical in the steering wheel has to run through it.

 

Well from the clock spring the wires are suppose to go into a analog to digital box just below the head unit. Then out of there to the cars wiring harness in the back of the head unit. I was hoping someone knew something that was just obvious that I was missing....

I have test voltage on most of the wires that I can find and not really finding anything that changes.

 

The steering wheel control circuit is very similar to a variable resistor. Different button presses result in different resistance through the circuit. For example, volume up might be 300ohm, channel down 1.2kohm, etc. You should be testing for resistance changes, not voltage.

On my 2003, the two wires for the steering wheel control circuit were grey/red and grey/black. If you put a multimeter across these and push the buttons, you should read different resistances. Then you'll know that these are the two you need to connect to your adapter. (my headunit labeled them control-ground and control-signal or something like that)

For my Chinese WinCE double DIN headunit, it accommodated the variable resistance signal natively without any adapter. I dont' know anything about your headunit, but you might want to double check that this isn't the case for yours before getting too deep.

 

I have a new pioneer head unit Pioneer MVH-X580BS

The back connections have a 3.5mm jack for remote and also a blue white wire for remote control.

 

Did the switches work with your previous radio?
......