what is the name of the part that the taillight harnesses plug into. on 2004 Cadillac Escalade

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
there is a small thin box mounted under the truck at the right rear quarter panel. all the tail light wiring harnesses plug into it, what is this part name or number.
tail lights work good if headlights are off but with headlight on they stop working. tap on this box and they will come on.
(0) Answers