Troubleshooting Trailer Brakes that Lock Up When Vehicle Brakes are Tapped
Question:
My truck has a new 7 way plug installed and when connected to our trailer all the lights and turn signals work, but when I start to pull the camper and I tap the brake pedal the trailer brakes fully engage. Where should I begin in order to diagnose the issue. Thank you
asked by: Paul W
Expert Reply:
One of the stop/turn signals on your trailer wiring is shorting out to the brake output which is putting full 12 volts on the brakes when the brake lights come on. To further figure out which blinker is the problem try putting on either blinker. You should see that one of the blinkers causes the brakes to lock up with each flash. That's the side that's shorting to the brake output.
From there you need to check all the connectors and wiring for a short between those two circuits and fix as necessary.
Product Page this Question was Asked From
Featured Help Information
Miscellaneous Media
Continue Researching
- Article: Trailer Wiring Diagrams
- Q&A: Trailer Running Lights Do Not Work but Brake Lights and Turn Signals Do Work
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Article: Brake Controller Installation: Starting from Scratch
- Article: Testing Trailer Brake Magnets for Proper Function
- Article: Troubleshooting 4 and 5-Way Wiring Installations
- Article: Troubleshooting Brake Controller Installations
- Q&A: How to Make an Adapter to Go from Semi Truck 7-Way Round to RV Style 7-Way Blade on Trailer
- Q&A: Will The Curt Dinghy Wire Harness # C96JR Interfere With Activation Of A Blue Ox Patriot
- Q&A: Trailer Turn Signals Both Blink when Just Left Turn Signal is Activated
- Q&A: Trailer Lights Left Side Turn Signal and Brake Lights Not Working
- Q&A: Troubleshooting No Running Lights on Trailer but Turn Signals and Brake Lights Work
- Q&A: Troubleshooting Lack of 12V Power at 7-Way Trailer Connector on 2019 Ford F-150
- Article: Trailer Lighting Requirements