If you aren't getting power back there, it isn't gonna work. However, if simply manipulating the tail light housing some suddenly makes it work for a while...... That has got to be a bad connection somewhere VERY near the tail light. If you truck has a trailer harness, I would start looking where the trailer harness hits the main rear harness.

 

I will update if I find or fix it side note do you know when the gas light comes on my gauge don’t work but my light do just wanna know for future reference

 

On mine, I have like 8 gallons in the tank when the light comes on, but, I am starting with a 34 gallon tank too.... generally, when the light comes on, it's time to start thinkin' about finding a gas station.