SwissHHR

Regarding the PIN layout above: are these RPO codes helpful?

UQ3 SPEAKER SYSTEM PERFORMANCE ENHANCED AUDIO (Pioneer version?)
UW5 SPEAKER SYSTEM BASE (non-Pioneer version?)

U2K DIGITAL AUDIO SYSTEM S-BAND
UE1 ONSTAR
UK3 STEERING WHEEL CONTROL

donbrew

Just that all of the pin positions are the same with different names.

Bxhhr

I have 06 HHR pioneer sub in rear stock head unit no on star just not sure if I need GMOs 3 or 4 and where is a good priced one

Oldblue

SwissHHR

Ok, so here's an update to my stock radio swap adventure: I got it to work with a used 2009 MP3 radio out of a 2LT. This radio was obviously already prepared for the UQ3 option (SPEAKER SYSTEM PERFORMANCE ENHANCED AUDIO) as the donor car had the Pioneer subwoofer. The first radio I had tried (2010 MP3 radio) didn't seem to be programmed for the UQ3 option. I could turn it on, everything looked normal, but there was no sound coming out of it whatsoever.

I also made a few changes to be able to connect a USB stick in the gloove box instead at the radio's front:
- cut a hole into the radio's back side and screwed the MP3 circuit board with the USB port to the back side (the MP3 circuit board is connected to the main circuit board with a ribbon cable, which allows it to be placed elsewhere)
- cut a hole into the gloove box' back
- ran a 70cm USB extension cable from the radio's back behind the waterfall through the instrument panel into the gloove box