I just installed a Pioneer AVIC-5200NEX in my C5. 

I have some issues and hope that those who have experience with the Pioneer NEX models and/or the Axxess XSVI-2004 adapter harness can point me in the right direction

I used the Axxess XSVI-2004 adapter harness and module to adapt the Pioneer to the stock C5 wiring harness and the stock Bose woofers in the doors, but had long ago replaced the Bose twiddlers in the doors and the rears with Kicker speakers.

I have installed many car stereos in many different types of cars and boats in the past with success........but this is the first C5 install.

I triple checked the harness wiring connections from the OEM harness to the AXXESS harness. Pics attached

1. The Pioneer remains ON when the car is turned Off.....not good.

2. The bass output is way below what I had with the stock BOSE head unit. Yes, I have tried many different settings in the Pioneer's equalizer.....but still almost no bass.

3. Is there a setting that will play my FLAC music files on my USB stick in a random order?

4. The rear and front cameras do not function regardless of what position the A4 shifter is in.

Any and all help will be appreciated! 

Thanks,
Jim

Here's what I found about adding a stereo to your car. hope it helps.

https://www.corvetteforum.com/forums/audio-electronics/3443290-axxess-xsvi-2004-factory-integration-adapter.html

As for the reverse cameras, you'll have to make sure the reverse signal wire is hooked up to one of the wires on the car that sends that signal. Don't know which one that might be honestly. Maybe this will help; https://www.corvetteforum.com/forums/audio-electronics/1117959-c5-and-general-audio-faq-5.html#post1564673611

This doesn't cover the Axxess but has a lot of info relevant to what you are doing.

https://www.corvetteforum.com/forums/c5-general/3651226-c5-double-din-install-guide-radio-cd-upgrade.html

The first posting in that link has a how-to PDF file:

https://www.corvetteforum.com/forums/attachments/c5-general/47884863d1431467226-c5-double-din-install-guide-radio-cd-upgrade-c5doubledinupgradepdf.pdf

Here's the first page of it...

Thanks for the replys

Well, it turns out the AVIC-5200NEX was defective, and beyond repair, or so they said.

My purchase price was refunded.

On to a search for a different head unit.

Thanks for all the input,

Jim