P2 Trailer Brake Controller Only Shows 4 Volts On Blue Wire No Matter what Gain is Set To

Question

Question:

I get 12+ volts when I use the manual control. But the max I get from the blue wire directly behind the controller is 4 volts no matter what I change the boost to or crank up the power too. Do you think the controller is bad? Or what could be the problem?

asked by: Butch

0

Expert Reply:

It does sound like there is a problem with the controller. But there are some things you can do to test it. In the truck cab you will need to sever the blue wire several inches from the back of the controller. Then use your meter to test the end of the blue wire coming out of the controller. It should only have power when you apply the manual override (or brake pedal on certain controllers but not the P2). If it shows power at idle then there is something wrong with the controller and it will need to be replaced.

If it tests fine then reconnect the blue wire. Then move on to the truck side trailer connector. Many times, dirt or corrosion can cause a short in a trailer connector. Make sure the truck and the trailer side connectors are clean and free of corrosion inside and out.

You can test the brake output pin and it should only show power with the manual override. If it shows power any other time then there is a short somewhere between the connector and the brake controller you will need to track down.

If the truck side checks out fine then it could be the wiring to the brake magnets or the magnets themselves. Inspect the power wires to the magnets and look for pinched, frayed, or damaged wires and fix as needed. Make sure the ground wires are attached to clean and corrosion free bare metal surfaces.

You can visually inspect the magnets and if you can see the copper windings coming through the magnets will need to be replaced. To further test the magnets you can follow the help article I have linked. I have also included some help articles on testing and troubleshooting brake controllers for you.

expert reply by: Michael H

0

Answer 1

Since you had the Curt Venturer Trailer Brake Controller part #C74VV installed and working on your 2015 Ford F-250, the problem is more than likely on the 2000 Ford F-350 and not on the controller. Your 2000 Ford F-350 could have come with either a…

view full answer...

Answer 2

The 12V wire at the vehicle-end trailer connector being hot even when the truck is off can vary depending on the application. For all aftermarket hardwiring installations of a 7-Way wiring harness, the 12V wire will be hot at all times, even when the…

view full answer...

Answer 3

The only wires that could be hot all the time on a trailer connector is the 12-volt hot lead, which is usually a black wire, and, if applicable, the auxiliary power wire, which is normally yellow or purple. The blue wire is usually for electric…

view full answer...

Answer 4

With the brake controller gain turned all the way up, you should be seeing closer to 12-volts at your trailer connector. You are losing voltage somewhere between the brake controller and the trailer connector. I am assuming that by electric brake…

view full answer...

Answer 5

It should be getting close to 12 volts if the power output is set to the maximum on the brake controller. Some brake controllers will not work properly if they are titled or turned to the side or if it has a leveler knob that is not level. Check…

view full answer...

Answer 6

If you are only getting 1.5 volts at your brakes then there is an issue, but there is not a fuse that controls the brakes. There are a number of possible issues so you will need to find out if the issue is on the brake controller, truck, or trailer.…

view full answer...

Answer 7

The Tekonsha P3 would need to be mounted so that it is level in the side-to-side orientation, and pointed so that it is parallel to the direction of travel. The controller does not have any error codes specific to the controller being out of…

view full answer...

Answer 8

You are correct, you should only be getting output when the brake is applied, or the override switch is activated. It sounds like the controller might be bad, but to make sure, you should probably bench test it before tossing it. Use a circuit…

view full answer...

Answer 9

Yes, if you test your brake controller output pin on your 7-way for voltage with the brakes applied and the gain set to the max you would see a full 12 volts. You should be able to adjust the gain to get varying voltages.

view full answer...

Answer 10

There are many things that can affect the voltage on the brake output wire from your brake controller to your trailer brakes such as the power setting on your brake controller, how you are testing the wire and if you are testing it with the brakes or…

view full answer...

Answer 11

The first thing to do is take a look at your owner's manual to locate any trailer fuses or relays and ensure they are all there and in working order. If they are, in order to determine the specific problem you will need to purchase a circuit…

view full answer...

Answer 12

First you want to test the brake output circuit on the 7-Way Plug with a circuit tester like part #PTW2992 with the manual override or brakes applied in the vehicle. If you are not testing the brake output circuit with either one of these activated…

view full answer...

P2 Trailer Brake Controller Only Shows 4 Volts On Blue Wire No Matter what Gain is Set To

Product Page this Question was Asked From

Featured Help Information

Instructions

Miscellaneous Media

Continue Researching