Trailer Brake Controller Shows Voltage on Blue Wire without Brake Pedal Pressed
Question:
Hello I have a 95 Ford 350 Diesel and my trailer brake control is a Drawtite Activator II. I am having trouble with my horse trailers brakes. The blue wire shows a constant 8 volts which increase to twelve when brakes are manually applied. Is this wire supposed to be hot or is the controller bad.
asked by: Stephen I
Expert Reply:
If the blue output wire is showing power when it should not be then that indicates that the controller is bad and will need to be replaced. But to test it properly you will need to sever the blue wire a few inches from the back of the controller. Then use your tester on the end coming out of the brake controller. If it shows power without the manual override or brake pedal being pressed then the control is bad and will need to be replaced.
If it works like it is supposed to then there is a short elsewhere that is going to the blue output wire. Usually what causes this is corrosion in the trailer connector. Examine the vehicle and trailer side connectors for corrosion on the pins and at the backs of the connectors where the wires attach.
There could also be a problem with the brake magnets or wiring. Examine the wiring and make sure there are no nicks with exposed wire touching metal. Also make sure the ground wires are attached to clean and corrosion free bare metal surfaces. Next inspect the magnets and if you can see the copper windings coming through then the magnets will need to be replaced.
You can further test the magnets by following the FAQ article I have linked for you. I have also linked an FAQ on troubleshooting brake controllers.
Product Page this Question was Asked From
Continue Researching
- Shop: Brake Controller
- Article: Troubleshooting Brake Controller Installations
- Shop: Hayes Engage Trailer Brake Controller - 1 to 3 Axles - Time Delayed
- Shop: Tekonsha Prodigy P3 Trailer Brake Controller - 1 to 4 Axles - Proportional
- Shop: Tekonsha Primus IQ Trailer Brake Controller - 1 to 3 Axles - Proportional
- Q&A: Should a Brake Controller Blue Wire have Voltage All the Time
- Shop: Tekonsha Prodigy P2 Trailer Brake Controller - 1 to 4 Axles - Proportional
- Q&A: How Much Voltage Should Be Applied To Brakes on Trailer w/ Electric Brake Controller
- Article: Aftermarket Brake Control Wiring for 07-13 GM Full-Size Truck with Factory-Integrated Brake Control
- Video: Trailer Brake Controller Wire Testing
- Shop: Marble Vinyl Flooring - Black - 12' Long x 8'4" Wide
- Shop: Large Coin Pattern Vinyl Flooring - Black - 18' Long x 8'2" Wide
- Search Results: fifth wheel hitch cover
- Search Results: triple axle fender skirt
- Search Results: hitch cover
- Search Results: flooring
- Search Results: wheel covers
- Shop: RV Roof Membrane
- Shop: RV Covers
- Article: Trailer Wiring Diagrams
- Q&A: How do I Tell if the Brake Controller is Bad
- Shop: Replacement Section for AC/DC Power Distribution Panel - 35 Amp
- Article: Testing Trailer Brake Magnets for Proper Function
- Shop: Gooseneck Hitch
- Search Results: interior door
- Shop: Trailer Wiring
- Q&A: Troubleshooting Low Voltage Output from Brake Controller
- Q&A: How Many Volts Should a Brake Controller Put Out on the Highest Gain
- Q&A: Should there be Power on a Brake Controller Blue Wire with the Brake Pedal and No Trailer Attached
- Search Results: prodigy p3