'13 C6 + 8200 NEX + RP5-GM11 + SWC = Really odd behavior!
 

I've got a '13 GS 3lt, Bose/Nav/Bluetooth car and I've just installed a Pioneer 8200NEX using the PAC RP5-GM11 interface.
The RP5 is set to 7, using the amplified connection port, using the 3.5mm jack to connect to the wired remote port on the 8200.

Here's the odd thing... If I leave the SWC connection (3.5mm) disconnected, everything on the HU works fine. The volume controls function normally, etc.

If I connect the SWC connection, then things get weird:
1. If I press the volume buttons (on the head unit.. not the steering wheel), it will change the volume in the intended direction and jump to a different band as soon as I let go (AM->fm1, fm1-fm2, etc)
2. If I hold down the seek button (in an attempt to scan for a radio station), it will do the same thing... seek, then change bands.
3. If I press the controls on the steering wheel, some buttons make it change bands (volume buttons), but none do what the manual says they should do.

Just in case... I've set the rp5-gm11 back to default (pressed the programming button once and waited for the 3 blinks...) - no change.


Any thoughts? This is really odd.

What happens if you leave the 3.5 jack out? What does it function?

I have a 2012 GS 3LT with Bose/navigation/bluetooth. I also installed the Pioneer 8200nex with the Pac Audio RP5-GM11 and don't have any of the issues you are describing. Are you plugging the steering wheel controls into the correct jack? There is also an Aux input jack, you don't want to confuse the two. Other than that I have no idea.

Yeah, really weird... Yep, I'm using the correct jack