Right turn signal not working on chassis

I've got a problem with right turn signal not working on any chassis that I have used the past couple of days. I tested the pig tail that connects to the chassis and did not get a signal on it like I would for the left turn signal. I then tried it from the plug coming from the cab and also no signal from the tester on right turn signal. I tried to see of i could open up to see if there was a loose wire but couldn't figure out how to open it without having to cut it. I uploaded pictures to see what im talking about. I also checked fuses with the tester and all were good. Can I open up this plug in the pictures to check the wires or will that mess it and will have to replace it? Is there somewhere else i can check before opening up the plug in the pictures. Any help would be greatly appreciated.

 

It's a 2013 kenworth t660