Trailer brakes -- good news and bad news

[dornoski]

I had a similar problem, my on board break control would give a warning “ Trailer Disconnected” I replaced the ground wire on trailer, same problem, ended up finding that the brake wire pulled through the dexter axel linking all brakes, was chafed from the build of trailer. That wire going through looks like 2 lead thermostat wire, I replaced all brake wire with the proper gauge from the 7 pin connector to the hubs. Stops on a dime now, by the way only 1 out of 4 brakes worked prior to my fix, I replaced all hubs and brakes as 3 of the 4 where rusted open

[dornoski]

Picture from my previous post

[hyperactive]

I had the same problem but not all the time, It was the brake wire that runs inside the axle tube wore thru the insulation and was shorting out. I replaced the wires and cable tied them to the outside of the axle on the back of the tube and all good now.

[Ol'Dan]

I had a similar issue with our 2015 24RKS and 2010 RAM. The truck had the Prodigy controller and worked well for about 2 years. The brakes began to grab regardless of gain settings. Then error codes started appearing on the controller. Trailer shop checked and verified trailer was OK. In checking the harness connector at the truck, all was OK but I noticed some corrosion so replaced it (very simple, snap out snap in). The problem persisted. Finally out of frustration I replaced the controller and the brakes worked smoothly again. Since that time I replaced the truck with a newer model RAM with factory controller and the brakes work fine which leads me to believe the first Prodigy controller was at fault. Hope your problem works out.

[DocBrown]

Did the trailer shop measure the voltage at the magnets? It doesn't sound like they pulled the wheels off. It's very unusual for a Prodigy controller to fail. And keep in mind it has a lifetime warranty, so if you can't find the issue, give Tekonsha a call.

My dad's trailer had similar issues. You could hear the brakes engage, and the magnets hum, and if you jacked up each side the wheels would stop if you spun them. Voltage was fine on the trailer side of the connector. But stopping power was terrible. Mind you this is an old trailer, but he insisted the brakes themselves were fine, and that the issue was with the Prodigy P2. I pulled his wheels and his magnets were visibly worn, and voltage at the magnets was almost none except for one magnet, which was only 9 volts. I replaced his magnets and rewired everything and now they work great.

I think you need to pull the wheels and inspect them yourself, and measure the voltage at each magnet. Work your way forward as the wires in the axles could be damaged, or somewhere else.

[Jmelvin]

The problem you are troubleshooting isn't voltage, it's amps. Your connector can show 12.9 volts or whatever, but that doesn't mean that it can supply the needed amps to apply the brakes. It only takes 1 (One) ohm of resistance to block the flow of amperage that makes the brakes work. It takes only a SLIGHT bit of corrosion to make one ohm resistance. The controller has to supply approximately 16 amps of power to fully apply the brakes (4 wheels). With 1 (one) ohm of resistance in the circuit it will not be able to push past 12 amps. That and the resistance of the brakes themselves, you will get no brakes. The wiring has to be PERFECT to get the brakes to work. The P3 has an amperage readout on the troubleshooting page. Hook up and apply full brakes, see how many amps you are supplying to the trailer. I made a test lamp years ago to test my truck. I took 2 reverse lights for my truck, wired them in parallel and hooked them to a seven pin plug to plug in my truck. When I applied full brake to the test lamp it took 17 amps to light both lights, perfect for testing the brakes. I hooked them to the blue wire (brake) and ground. I had to replace the light guage wire that the factory put in my pickup and solder all the connections. The push on connector at the connector by the bumper was the major problem. If you clean it up to pristine it might work but it is going to corrode shortly and the problem will be back. I'm surprised more people don't have the same problem.

[sfran]

What Doc says. Those magnets take a beating.

[cwilly8]

All the suggestions are much appreciated. Unfortunately a well known virus has had me down for a few days. I'll get back on the problem next week.

[cwilly8]

One other comment: When I took the trailer to the shop, they brought out a test box and plugged it into the trailer side connector. When I idled forward, they applied the brakes using their test box and we stopped. When I actuated the lever on the controller to apply the brakes, we did not stop. Their conclusion was that the trailer side is OK.

[Yooper906]

Originally Posted by cwilly8

One other comment: When I took the trailer to the shop, they brought out a test box and plugged it into the trailer side connector. When I idled forward, they applied the brakes using their test box and we stopped. When I actuated the lever on the controller to apply the brakes, we did not stop. Their conclusion was that the trailer side is OK.

From my previous post, amperage is half the equation, volts is the other half. I'm familiar with the box they plugged into, the box has a good known power supply to furnish the volts and amps to the trailer brakes, and will measure both.

Glad you found something, at least you have narrowed it down to the controller, wiring, 7 way connection. All truck side.

[GreyWolfWpg]

Did you end up finding out what is causing your issue? I’m having the exact same problem myself.

[cwilly8]

[Long hiatus since the last post]

Today I connected the TV to the trailer to check the Prodigy P3 controller in the Troubleshooting Mode.
1. Battery Voltage was correct
2. Brake Voltage was correct with brakes applied
3. Output Voltage was 0.0 volts (with brake pedal depressed fully)
4. Output Current was 0.0 amps (with brake pedal depressed fully), went up to about 8 amps using manual lever on controller

This seems to point to a faulty controller.
Your thoughts are appreciated.

[craigav]

Originally Posted by cwilly8

[Long hiatus since the last post]

Today I connected the TV to the trailer to check the Prodigy P3 controller in the Troubleshooting Mode.
1. Battery Voltage was correct
2. Brake Voltage was correct with brakes applied
3. Output Voltage was 0.0 volts (with brake pedal depressed fully)
4. Output Current was 0.0 amps (with brake pedal depressed fully), went up to about 8 amps using manual lever on controller

This seems to point to a faulty controller.
Your thoughts are appreciated.

From what I read, you are expecting brake output voltage when you press the brake pedal, however that is not how the controller works. It only outputs brake voltage when its internal sensor detects a deceleration of the tow vehicle (inertia sensor) or when using the manual lever on the controller. Pressing the brake pedal hard, soft, a little, or a lot makes no difference to the brake controller when sitting still.

The results you posted while troubleshooting are the results that should be expected. ~CA

[Jagiven]

Originally Posted by craigav

From what I read, you are expecting brake output voltage when you press the brake pedal, however that is not how the controller works. It only outputs brake voltage when its internal sensor detects a deceleration of the tow vehicle (inertia sensor) or when using the manual lever on the controller. Pressing the brake pedal hard, soft, a little, or a lot makes no difference to the brake controller when sitting still.

The results you posted while troubleshooting are the results that should be expected. ~CA

My P3 does not output any voltage when I am just sitting still.

[DocBrown]

X3, use the manual lever to apply voltage. Sitting still and applying the brake applies no voltage. You can also have someone pull the lever while you measure voltage at the connector and at your brakes. This is what I was alluding to in my previous post.

[craigav]

I would suggest reading the brake controller manual. I had thought about mine (P2) and remembered that the controller does have some activity based on the brake pedal, first being that if you hold the tv brakes down past 5 seconds, the controller will engage the brake circuit at 25% of the power setting and is documented as the "HOLD" feature (same for P2 and P3), and also if you need to back up a hill, you can disable the boost and\or hold by pressing the boost button for 5 seconds while the brake pedal is depressed. The second aspect is that I believe that the boost mode triggers off of the brake lights (pedal).

However, keep in mind that pressing the brake pedal while sitting still, does not provide proportional output current to the trailer brakes, but there should be some power (25%) applied to the trailer brake circuit when holding the brake pedal down past 5 seconds. ~CA

[cwilly8]

I appreciate all the replies. Here's the latest:
I borrowed my father-in-law's Silverado pickup truck (factory controller). When connected to the trailer on our gently (downhill) sloped driveway, I rolled backwards and fully applied the manual controller output. There was zero braking. With my wife at the wheel, I could hear a hum from the brakes, but they did nothing to slow the rolling.
Am I correct in concluding that this isolates the problem to the trailer and/or brakes? (We had the same results with our Durango and the Prodigy P3 controller.)
My next step will be to go under the trailer and follow the wiring to see if I can find a poor connection that would impede the current.

[mrmom]

Trailer brakes will NOT work going backwards! The magnet has to "pull" against the drums rolling forward to turn the cam and expand the brake shoes. The hum you hear is probably the magnets working to apply, but they can't apply any force when the drums are turning in reverse!

[cwilly8]

Sheesh! I'm in way over my head on this. Thanks for the continuing education!

So I'll get the pickup truck again and go to a parking lot where I can adequately test the brakes.

[craigav]

Originally Posted by mrmom

Trailer brakes will NOT work going backwards! The magnet has to "pull" against the drums rolling forward to turn the cam and expand the brake shoes. The hum you hear is probably the magnets working to apply, but they can't apply any force when the drums are turning in reverse!

Actually they work in forward or reverse. However they don't work as well in reverse usually. Whenever the magnet moves forward or backwards, that action of the magnet spreads the brake shoes apart. In any case, I would suggest only testing when moving forward for best results. ~CA