Does anyone know how to wire a third brake light on a shell? Which wire is the brake/taillight?

 

What year Dakota do you have? Body style?

It should be equipped already. Check near the spare tire. If I remember correctly you'll find it down around there.

 

It is a 99 two wheel drive.is it a single wire or Ina cluster?

 

It was just one or two wires if I recall. It should be there.

 

It may be in your interest to grab a Hoppy trailer connector harness. It plus into the chassis/body wiring harness connector and breaks out everything nicely.

 

Years ago I tapped into the wires going to my tail lights and ran them into the bed of the truck. I then used insulated spade connectors so I could remove the cap if I needed to then hook it back up easily. I used connectors with different colors of insulation and switched the male and female ends when I installed them so I couldn't hook them back up wrong when I reinstalled the cap. Worked like a charm. I installed both a third brake light and running lights on the rear of my cap.