Installed aftermarket radio w/ PAC RP4-GM31 interface, Reverse output not working

[eventsb]

Hello,

This weekend I set out to install a Pioneer aftermarket head unit in my new to me 2013 PPV. I am using the PAC RP4-GM31 radio replacement interface which says it provides VSS, parking brake, and reverse output signals. I am obviously wanting to use an aftermarket backup camera with this system. When I wired it up I noticed the parking brake output works fine but I am seeing no activity on the reverse output wire. It just stays at 0V all the time. Therefore, the head unit is not able to automatically switch to the camera when in reverse.

Has anybody else ran into this issue?

Is there something wrong with my interface?

Does my BCM need reprogamming?

Or something else entirely?

I've used PAC interfaces on a handful of other vehicles with great success in the past, so I am quite familiar with their products and how to install them. This one in particular has me stumped though.

 

[mikez71]

I would check for any cut wiring.
Do your reverse lights work?
And what color is the reverse output wire? This is lights diagram, but there could be other wiring I didn't find.

 

[eventsb]

I would check for any cut wiring.
Do your reverse lights work?
And what color is the reverse output wire? This is lights diagram, but there could be other wiring I didn't find.


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View attachment 429290

The PAC interface operates via the CAN bus, there is no "reverse light" wire in the back of the radio. It gets all its inputs from the CAN bus. When it receives the message that says the vehicle is in reverse, it toggles the puple/white wire from 0V to 12V. Considering the parking brake output works, I'm inclined to believe there is something wrong with the interface itself. But I have no way to confirm I will double check the reverse lights and report back

 

[Alessandrolomb]

You should make sure the reverse output wire from the PAC interface is connected to the reverse signal input wire on the Pioneer head unit. This wire is usually purple and white on most head units. Double-check to ensure it's connected properly and secure.

 

[eventsb]

Yes, it is. I also am confirming with a multimeter on the PAC interface that the purple/white wire does not ever change from 0V.

The reverse lights are working BTW.

 

[eventsb]

UPDATE: After trying a second RP4-GM31 and it still not working, and reaching out to PAC support, I have arrived at the conclusion that the PAC RP4-GM31 radio interface module simply is not interpreting the CAN messages properly or the BCM is not sending those messages out when the vehicle is put into reverse. I had to manually trigger the reverse signal by tapping into the backup lamp control wire on the BCM connector. Not really the way I wanted to go about this but it is what it is. Hopefully this helps anybody else with a PPV having issues with the reverse output on their PAC RP4-GM31.

 

[Fubar0715]

I have an aftermarket HU and camera in my SSV - had to tap into the reverse light wiring to make it all work. I dont remember what interface module I used but ran into same issues you describe here.