Another schematic that may help isolate your DATA BUS communication troubleshooting for a common point of failure.

 

@FFMetal

The Pioneer Head units are usually excellent also the 2007 does not have CAN bus but Class2 Serial Comms. Any water ingress to this serial bus could be a problem, as is any faulty module or aftermarket equipment (radio, alarm etc) connected to it. Also if air suspension has been removed (springs fitted) check the 16-Way IP connector originally plugged into it, if not sealed water could have invaded the contacts etc. SP205 has removeable links which can help isolate comms issues. This video may help:-

Not sure why the installer left wires hanging etc, my Pioneer has all the wires and module tucked neatly to one side of the unit.

@bronxteck 's suggestion about the interface module is valid as is @PGI Conch 's diagrams and suggestions about grounds. Any bad ground connection to an electronic control module could cause a problem, again @PGI Conch 's ground list is very helpful

Also dielectric grease is an insulator, take care not to get any on the contact surfaces, check the ground wires and pins to make sure they have very low ohms to chassis (<0.1)

 

Thank you very much for that info. I wasn't aware of the air suspension. If it had it it was removed, but i don't think this came with it. No fuse for it anyway. I'm planning on pulling everything this next week after the holiday and using the diagrams tracing everything

 

It would be worth checking to see if it's 16-Way connector is in the harness, it's located around the Right Rear suspension.

Fuse or no fuse makes no difference, corrosion around the data lines can short communications.

 

Per Oceans suggestion the 2 connectors that would have been connected to the air suspension look like this and will be hanging near the center to right side under the rear bumper area.