Will Pollak 7-Way Tester Show Issues on Brake Output Circuit for Brake Controller

Updated 03/02/2026 | Published 02/28/2026

Question:

My daughter has a 2019 f150 and I am wanting to know if this tester will tell me if her brake controller is working or not. When the trailer is hooked up I can use the brake controller to stop the trailer and it has a strong readout but if I use the brakes on the truck is doesnt seem to work. Would this tester show where the problem is

asked by: Tracey W

Expert Reply:

Hey Tracey, the Pollak 7-Way Tester part # PK12741 has a light indicator for the brake output circuit so if your brake controller is working you will see it light up as the brake controller ups the voltage. If what you described is that the override lever of your brake controller can activate the trailer brakes but the brake pedal does not activate them that is going to be an issue on the red wire of the brake controller. It would need to be connected to a circuit that only sees voltage when the brake are applied. Sometimes its just a blown third brake light fuse that causes this problem but otherwise it would be a connection issue on that red wire between the controller and the vehicle. Was I understanding your issue?

The circuit is labeled BK for brake that you can see in the attached picture.

expert reply by: Jameson C