Montruck

Trailer shop rewired my trailer light connector, which had rotted out. Replaced with a 4 pin connector. He tapped into the right and left rear turn signal wires going to the rear lens connectors. Turn signals work, but when step on brakes, they stop blinking, and the stop light goes dimmer. With or without the trailer hooked up. 1997 f159 4x4. Any ideas? I will probably take it back to shop next week, but I have to go on a trip on Sunday, so will be out of town; trying to get it to work meantime.

JCH841

Crossed wires, possibly mixed taillights and brakelights.

etrailerTeam

Since you've paid them to do the work, I'd be inclined to strongly encourage them to fix it correctly. If you need to leave right away, or if returning it to the shop isn't convenient at the moment, do a standard troubleshoot as described in the provided link:

https://www.etrailer.com/expert-84.html