Troubleshooting Trailer Brakes Getting Only 8 Volts Of Power
Updated 07/27/2025 | Published 05/01/2017
Question:
I put new shoes on the travel trailer on all 4 wheels the drum, back plate and magnet were in good shape The brakes are working but not stoping like it did before I turn the brake controller all the way up and Im only getting 8 volts to the brakes and 8 volts to the plug on the back of my truck 2008 Dodge Ram hemi also pulled the emergency pin Plug on the travel trailer and still it was 8 volts to the brakes Im wondering if my brake controller is bad
asked by: Randy
Expert Reply:
If you are only getting the 8 volts when you pull the pin using a meter like # PT89ZR, that has nothing to do with your brake controller as the breakaway battery is powering that from the trailer itself. You can confirm your brake controller is working properly by checking the 5 o'clock pin on your 7 way with your meter when the trailer is disconnected while having someone hit the manual override on your brake controller.
You most likely have a bad ground in your wiring on your trailer. Check the grounds near your brake assemblies for corrosion or rust and make sure there is a clean metal to metal connection. Check your voltage again, and if that didn't solve it, check all other trailer grounds. If that doesn't solve it, you will need to trace your brake wires to locate a short. Check visually first and then with a tester. Replace wire as needed.
Your brake magnets could also be an issue, so I recommend testing them with a battery and your voltage meter. I've attached an article to help. While you are in there testing magnets, you will want to make sure you have adjusted your brakes shoes properly. There should be a slight drag on a spinning wheel when adjusted properly.
Product Page this Question was Asked From
Digital Multimeter with 42" Long Test Leads - LED Display
- Electrical Tools
- Testers
- Multimeter
- Yellow
- Performance Tool
more information >
Featured Help Information
Instructions
Miscellaneous Media
Continue Researching
- Search Results: 7 pin trailer plug
- Shop: Trailer Hitch
- Shop: Brake Controller
- Article: Testing Brake Controls
- Shop: Trailer Wiring
- Shop: Dexter Nev-R-Adjust Electric Trailer Brakes - 10" - Left/Right Hand Assemblies - 3.5K
- Shop: Trailer Hub and Drum Assembly - 3,500-lb Axles - 10" Diameter - 5 on 4-1/2 - Pre-Greased
- Shop: Hub Bearing Kit for Lippert, Dexter, and AL-KO Axles - 3,500 lb with #84 Spindle
- Shop: etrailer Trailer Hitch Receiver - Custom Fit - Matte Black Finish - Class III - 2"
- Article: Brake Controller Installation: Starting from Scratch
- Shop: Vehicle Tow Bar Wiring
- Shop: Spare Tire Cover
- Shop: Gooseneck Hitch
- Search Results: tekonsha trailer brake controller
- Shop: Kenda 205/65-10 Bias Trailer Tire with 10" Galvanized Wheel - 5 on 4-1/2 - Load Range E
- Search Results: led combination tail light
- Q&A: What Gauge Wire Should be Used to Wire Trailer Brakes
- Search Results: caliber
- Search Results: trailer safety chains
- Q&A: Installing the Prodigy P3 Brake Controller on a 2018 Toyota Tundra
- Q&A: Grounding the Tekonsha Prodigy P3 on a 2017 Toyota Tundra
- Q&A: How Many Volts Should a Brake Controller Put Out on the Highest Gain
- Article: Testing Trailer Brake Magnets for Proper Function
- Shop: Easy Grease Trailer Hub and Drum Assembly for 5.2K & 6K Axles - 12" - 6 on 5-1/2 - Pre-Greased
- Q&A: How to Initially Adjust the Dexter Nev-R-Adjust Electric Trailer Brakes
- Q&A: Troubleshooting Trailer Brake System That is Only Showing 5-Volts at Trailer Connector
- Search Results: trailer led brake lights
- Search Results: trailer hubs and drums
- Article: How to Measure Your Trailer Wheel Bolt Pattern
- Video: Dexter Trailer Hub and Drum Assembly Spec Review
on Automotive Tools
Paul
7/27/2025
I connected my battery charger to my trailer brakes through my junction box and then checked my voltage with meter at several spots in my wiring going to my brake and only have 8 volts.