Trailer Wiring: Right Stop Lamp Doesn't Work

[hagsg20]

2005 Chev Avalanche, 5.3L, Flex Fuel, Z71, 4x4

 

I'm having a weird problem with my trucks factory trailer wiring. I have the 7 pin connector on the back with the reverse light wiring. First off, let me say that the trailer I am using works fine - it's just your basic utility trailer. I've tested it on multiple vehicles to rule out the trailer wiring itself. Here's the problem: I have no RIGHT stop lamp on the trailer. LEFT stop lamp works fine. Every other light works on the trailer EXCEPT the RIGHT stop lamp.

 

I put a tester to the 7 pin connector on the truck and had a buddy go through the turn signals, running lights, etc. while I tested for voltage. No power to the pin that powers the right brake lamp - but only when applying the brakes. There IS power to the pin when you toggle the right turn signal - it's the same wire, I am truly confused!

 

I have also gone through every fuse associated with the trailer lighting - all good. And the wiring itself looks good.

 

Is there some sort of trailer module on the truck that controls the trailer brake lighting?

Could that be the problem? Where is it located?

 

Any help I could get would be much appreciated!! Thanks