No brake light

Brake light switch usually air pressure switch. Somewhere under cover or dashboard.

 

That's nothing that came from a factory with the end that jacked up.. stripped and twisted..

 

I can find you some legitimate wiring with the last 6 of your vin.

 

So one thing to note in your T/S is that the SERVICE BRAKE pedal has no switch on it--it is an air pressure switch on the air manifold denoted as STOP LT SW below. It's circuit is denoted as 36 & 36B (A).




I would first check out the switch itself and the associated circuits.
Then you need to check the PDM.



Here is where the switch is located--on the bottom right there you see the harness.



Here's you PDM:



Find the one that says STOP LT:



This circuit then goes to your turn sig switch from the PDM that then controls your 39R and 39L (which is your combination lamps):



From there you should then be able to find your problem.

Hopefully that makes sense and then assists you in your trouble-shooting. If not, then I would take your truck to a certified FTL dealer to fix.

 

@Dorego401 Yes. Here's a better diagram: