Third Brake Light Issues

I have a 2016 with a Leer Camper Shell. I have my third brake light for the shell tapped into my drivers side brake light. The 3rd brake light works on the shell fine, but when I turn on my headlights, my drivers side brake light does not work when the brakes are depressed. Any and all help would be appreciated. Such a small issue but it drives me crazy.

 

Is this a problem that just started and was working fine before?

 

No, my brake lights have always worked fine until I recently wired up my shell, and somebody told me it wasnt working.

 

If I disconnect the third brake light from my camper shell, the brake lights work just fine with and without the headlights turned on

 

you positive your wired to the brake light and not the taillight?

 

Yeah I wired to the lower harness which is the brake light on the third gens

 

how is the light on the shell grounded?

 

inside the bed on one of the screws, I took a grinder under where the head of the screw and grounded it there. Which makes me wonder even more because all the brake lights work properly when the brake is depressed when my headlights are turned off. When I turn my headlights on is when the drivers side brake light doesn't work when the brake pedal is depressed

 

so you have the positive wire (one wire)run to the left rear tail light?

 

Its ran to the tail/brake light. THe top bulb is for blinkers and tailights, the middle bulb is the tail/brake light and the bottom bulb is for reverse. I tapped the blue wire on the bulb with the positive from my third brake light inside the shell

 

Ditch your homemade wiring and use this plug & play harness.

https://fbchs.square.site/product/t...true&sa=false&sbp=false&q=false&category_id=6

 

this worked like a charm, plus no cutting, splicing, grounding.

 

Post pics of the wiring job.

 

^

This. I run a few different things from them on both trucks.

 

Now that I've made 3 trips to the store and discovered it may be a bulb issue. I've replaced the bulb 3 times and same issue. Brake light bulbs have 2 fillaments and only one is illuminating when I press on the brakes. I have completely disconnected the third brake light from the camper shell. My brake light does not work with my headlights lights turned on

 

Brake bulbs have two filaments and one should come on (dim) when headlights are on and the other should come on brighter when brakes are on.

Camper 3rd brake needs to be wired to whichever wire corresponds to the bulb filament that is brighter and for braking. I don’t know if blue is that one.

you probably need a better ground than a bed screw. At the very least test that screw for continuity with a known ground point so you have confirmed good ground. The best idea would be run your ground back to one of the tail light bulb grounds.

As already requested, pics of your work would help. The problem as it’s being explained really does not make a lot of sense and the info provided makes me kind of question where to begin helping.

 

only one filament should work with brakes....the other filament is taillights...
check for 12volts with brake pedal depressed...is there 3 wires on that plug,one is ground,.....one is taillights and the other is brake?

 

Only one filament is lighting up even when the brakes are depressed. The light is significantly dimmer when brakes are pressed on drivers side than on passenger side. Not sure if its a bulb issue or issue with voltage