Trailer Brakes Lock When Tow Vehicle Turn Signals are Activated

Published 02/13/2016

Question:

my controller is locking up the brakes when the turn signals are on

asked by: Lee

Expert Reply:

The two most likely culprits of the malfunction with your trailer brake controller # 5054 you mention is that the trailer connector on the tow vehicle is severely corroded and allowing the voltage meant for the turn signal circuit to bleed over onto the brake circuit. Check the pins on the trailer connector (both on the vehicle and on the trailer) for green or white corrosion. If the connector is corroded, there's a chance the corrosion has spread to the interior of the connector and is causing the signals to bleed from one circuit to the other. If the connectors are corroded, replace them. If you'd care to reply with the year, make and model of the vehicle, I'd be happy to recommend replacements.

The other possibility is that the trailer connector or the connector on the vehicle isn't wired correctly. Review the way the connectors are wired and compare them to what's shown in our trailer wiring FAQ article which I've linked for you. If you're using a 6 to 7-way adapter, it's possible that the adapter is wired wrong.

expert reply by: Mike L