2019 Pete 567 Concert Class Radio no stations

Hi guys,
2019 Pete 567 with a concert class radio. The FM Radio turns on, but barely gets 1 station. I've replaced the CB antenna and the radio antenna located on the roof with OEM replacements. I took the unit out and installed it in another truck and got all the stations. This tells me that the head unit works fine. I have my local Pete dealer looking into a wire schematic for me but they don't sound optimistic.

There is a PMG located in the headliner. Not sure if that's somehow related.
Any thoughts on a direction to diagnose and fix the issue?

 

The radio from truck #2 did NOT work in truck #1.

 

Peoplenet Mobile Gateway. It's a black box up in the headliner.

What's a diplexer and where would that be located?

 

So it would have the CB and Radio antenna plugged into it correct. I believe that is what the Peaplenet Mobile Gateway box is, there's also a Wifi antenna on that box (not used). It has something to do with E-Logs but it's on a dump truck so we don't use E-logs.

 

Thank you for your time on this. I will take a look and report back.

 

Here's what I found. This truck, 2019 Peterbilt 567 does not have a diplexer. The CB and Stereo have separate antennas with antenna cables running directly to them. I tested the FM/AM radio antenna cable for continuity and found it was an open circuit. There is a connection for the FM/AM Radio antenna behind the left kick panel. Pull the fuse box cover (below the data port and behind the clutch pedal), and remove the panel to the left (against the door jam) and you will find the connection. You'll have to remove the grab bar to gain access to one screw. The connection came unplugged. I recommend wrapping it in electrical tape as the connection twist lock isn't very tight.