Maybe someone hear has a answer rear lights not working.

are they the right lights and did you install them correctly

 

Fuse,. Broken wire bulb

 

Check your fuses and your wiring at the rear. Make sure there are no barely wires chaffing causeing the short. Winter can be very harsh on rear light wiring, road salt and grime if you run in bad weather also extreme vibration at the rear of the truck

 

Check the fuse and that there is power at the fuse then check for power at the transmission switch. Finally trace the wiring from the transmission switch to the light.

 

I recently had a similar issue with my company tractor brake lights not working on my company 2018 Peterbilt 579.

The shop checked the fuses and other usual suspects, but came up empty.

Anyhow, the tractor was taken to a dealership for repairs. I don't know what repairs were performed, but I am guessing a few wires were replaced as I noticed that the rubber flooring was reinstalled poorly indicating a not-so-quick repair took place.

My suspicions are that the previous driver caused an electrical short by overloading one of the 12v outlets.

May your repair be simple and not costly.

 

Break switch on break pedal

 

You guys know that there are relays that are in line for the power to the lights, this is to allow power distribution design based on loads.

 

Typical Dealer BS. Stuff like that always burns my hide, for the amount of money that they charge. You should get it back without any flaws to the work that they preformed

 

The truck threw a fault for SHORT CIRCUIT. That means a wire has rubbed thru on another wire or against a metal part of the frame/cab. If it was a blown fuse or broken wire, it'd read OPEN CIRCUIT. The truck already diagnosed the fault lol. You just gotta find the short. Because there is a fault for this issue, that indicates that the circuit is controlled by a module. In the event of a short, it won't even send power to the circuit once it detects the amperage draw is too high.