Correct Pin Out for Truck and Trailer 7-Way Blade Connectors

Updated 08/25/2020 | Published 06/12/2019

Products Featured in This Question

Pollak Replacement 7-Pole, RV-Style Trailer Connector Socket - Vehicle End

(768)

$14.85

Pollak Black Plastic, 7-Pole, RV-Style Trailer Connector - Trailer End

(737)

$8.14

Question:

Which manufactures use trailer brakes wiring with a 7 blade flat light connector. One style is power for brakes on a outside blade and the other style center pin is brakes, always have this issue. When I rent a chipper it’s always a problem cause my truck locks the brakes, so which style is more widely used, so I have less problems and it’s not just the wire colors cause when I go to buy a 7way to 6 way there are two different wiring ions

asked by: Ben

Expert Reply:

Attached are some photos of the typical wiring functions for truck and trailer 7-Way blade connectors, like parts # PK11893 and # PK12706. If you typical pull a trailer that has a 7-Way connector then you want to follow the pin out diagrams I mentioned. If the chippers that you tow have a different configuration then the Hopkins Adapter # HM47535 will likely do the trick because you can change it so that the center pin is either related to the electric brakes or the 12V power.

If you are talking about different connections please let me know and I'd be happy to help you out! You are correct that the color wiring isn't the best way to try to wire connectors as those colors can vary per function.

expert reply by: Jon G

click to enlarge

You W.

3/10/2020

I cant get a 2015 Chev pickup to light up a trailer that works on older trucks. They turned the plug upside down.

Chris R.

3/11/2020

Have you tried testing the pins on the factory 7-Way with a circuit tester to see if they are getting power with the light functions activated? Is it just one function not working on the trailer or is it all of them?

Eric W.

8/2/2020

I have a flat car hauler with 7 pin connector. Trailer brakes work and truck says they are connected (integrated brake controller). Truck also says trailer is not connected I think because lights do not work. I think it's bad ground through the hitch. Can I splice into the white ground wire that goes to the brakes and ground that to the frame up near the hitch ?

Chris R.

8/12/2020

The issue you're having could definitely be from a weak ground connection, but I'm not sure splicing into the brake assembly ground wires will help. How do you currently have the main harness ground wire attached?

Eric W.

8/12/2020

@ChrisR The white ground from the harness goes back to the brakes on the first axle, splits and goes to the second axle. (as new). So they only connect the brakes. Ive cleaned the ball hitch and the inside of the trailer hitch, lights will work sometimes now, but then fail once I start moving forward. The truck is a 2019 silverado with trailer package and integrated brakes.

Eric W.

8/16/2020

@ChrisR The white ground wire goes to the brakes on the first axle. There it splits and continues to the second axle. There is no additional ground wire for the harness. If I backup the truck just a little, the truck sees the trailer, pulling forward, it looses the connection. I presume this is due to the hitch getting a better connection to the ball.