Odd Brake Controller Problem

[Kevin A]

I have a Prodigy 3 controller installed in our Ford Expedition, which came with the wiring harness installed. Lately, when pulling our Silver Cloud, the display on the controller will occasionally turn red with the short/no brakes warning. However, touching the foot brake or using the manual control on the unit will return the display to green and the trailer brakes engage. I can feel the brakes engage, so I know they are working. When driving without the trailer, the controller display always stays green.

Other threads on a similar topic have indicated this as a bad ground or wiring short somewhere. However, I would think that a bad wire/ground would cause the brakes to not work at all at times.

Do you think I have a bad controller or what should I check? By the way, this happens without any big bumps, so it wouldn't seem to be a wire bouncing back and forth. Also the 7 pin plug on the trailer has been replaced since this issue first popped a few months ago and I've checked all wheel brake electrical connections for tightness. Remember, the brakes do work!

Thanks!

[John in Michigan]

FYI, a problem reported and solved a couple of weeks ago had to do with:

- Prodigy brake controller intermittently displayed "short" warning while towing.
- The owner finally determined that indeed the blue brake wire was intermittently shorting as it had rubbed bare against the exhaust system under the tow vehicle.

In that particular case, the Prodigy brake controller was accurately reporting the problem. A good thing.

[John in Michigan]

So when the Prodigy P3 displays "short" and assuming the Prodigy P3 is working correctly:

- Look for a short between the blue brake wire and ground/frame. The blue brake wire runs from the brake controller all the way back to the brakes.
- Other possibility is worn out brake magnet (mentioned by other on this forum).

[John in Michigan]

Here is the etrailer recommendation for testing brake magnets:

https://www.etrailer.com/faq-testing...-function.aspx

Also, with the Prodigy P3 you can actually check how much amperage the brake magnets are drawing by going into Help > Setup > Troubleshoot > Output Current.

[Raspy]

If I remember correctly, while discussing this on the Oliver forum, the problem can be a bad ground wire from the tow to the trailer frame. In some cases the brakes are grounding through the trailer ball and will work, but will also give the warning because the connection is so poor.

A quick test would be to identify the seven pin plug ground wire and make a temporary connection from there to the trailer frame. Or find the other end of the umbilical, inside the trailer, and make sure the ground wire has a physical connection to the same point as the brake circuit negative and the battery negative.

In my case, the brakes worked, but I got no charging through the umbilical. I just needed to run a jumper from the battery negative connection to a frame lug.

[Kevin A]

Thanks, guys. When we go pick up the trailer and hook up on Friday, I'll run the diagnostic tests in the P3. I'll also some ground and wire checks.

[Raspy]

Kevin,

While looking for a possible ground (or Negative) problem, you could do something as simple as hooking up a battery jumper cable from the truck frame to the trailer battery negative terminal. See if this solves the problem. If so you can begin look for the problem.

[Markz]

Originally Posted by John in Michigan

FYI, a problem reported and solved a couple of weeks ago had to do with:

- Prodigy brake controller intermittently displayed "short" warning while towing.
- The owner finally determined that indeed the blue brake wire was intermittently shorting as it had rubbed bare against the exhaust system under the tow vehicle.

In that particular case, the Prodigy brake controller was accurately reporting the problem. A good thing.

Exactly true. Same problem I had. The insulation had been burnt away from the brake wire. Everytime I touched the brake petal it shorted to the muffler. I re-insulated the brake wire and zip tied everything well away from the exhaust. Hasn't been a problem since.

http://www.fiberglassrv.com/forums/s...ad.php?t=85816

[Markz]

Hope it helps.
The members here had some great suggestions on hunting down the short.

[bigb]

Let us know how it works out. I had the same issues with a P2 last summer and customer support told me it was a bad connection somewhere. I intend to replace the P2 with a P3 and I also ordered a new OEM 7 pin socket with harness because mine is older. On my Ford it will just plug into the frame harness near the spare tire.