Adapting a 5-Way Flat Vehicle Side Trailer Connector to a 4-Way Flat for Towing Lights

Updated 05/15/2020 | Published 05/20/2011

Products Featured in This Question

Adapter 7-Pole to 4-Pole and 5-Pole

(121)

$32.33

Hopkins Endurance 5-Way Flat Trailer Wiring Kit - Vehicle and Trailer Ends - Ergonomic Design

(37)

$21.19

Question:

Can some one who has a 5 pin flat from the car and a set of tow trailer lights 4 pin flat use this to connect them together ..... adapter 7 pole to 4 pole and 5 pole....? If not is there an adapter ? Thank

asked by: Glenn B

Expert Reply:

You may be able to plug in the 4-Way flat into the 5-Way flat without an adapter. There will just be one pin that is not used by the 4-Way left over. All the other functions will still work. The pin furthest from the ground pin (on the vehicle side 5-Way) will be the one that is not used.

If the two connectors will not fit together, you can use Wiring Kit, # HM47890. You will just need the trailer side of the kit. You will have to replace the connector on the tow lights with the trailer side connector in this kit, leaving the blue wire taped up.

The Hopkins Adapter, # 37385, is made to be plugged into a vehicle that has a 7-Way connector. It then provides 4 and 5-Way flat connectors to plug in a trailer.

expert reply by: Michael H

Gary J.

5/13/2020

does the blue wire on 5 flat plug control the brake, or the brake lights.

Chris R.

5/15/2020

The blue wire on a 5-Way connector would carry the reverse light circuit. On a 5-Way connector there isn't a circuit for the actual brakes - this would be activated either by inertia (if you have surge brakes) or it would need to be upgraded to a 7-Way connector (along with adding a brake controller in the tow vehicle) if the trailer has electric brakes.