No Brakes

[tthomison]

Have a 2020 Reflection 315. The electric brakes are not working. Have had both plugs replaced, trailer and truck. Ford dealer has replaced the brake controller. Did not help. Dealer then connected a different truck to the trailer and still nothing. Both trucks show a "trailer wire fault". All other lights on the trailer work. Turn, brake and lights. The only thing not working are the trailer brakes. In reviewing the wiring diagram, it shows a 400a in line fuse. Does anyone know where the fuse is located? Any other suggestion would be very helpful. Thanks

[315RLTSinPA]

There shouldn't be a fuse on the brake wires.

[FT4NOW]

The trailer wiring fault message on a Ford means there is a short on the trailer brake circuit and will not apply power to the brakes in that case.

Have you recently replaced wheel hubs or anything? Maybe a wire got pinched and now is contacting the frame. Also could be an issue with your break away switch failing. If you have a multimeter, you can start troubleshooting.

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[fez111]

The trailer wiring fault message on a Ford means there is a short on the trailer brake circuit and will not apply power to the brakes in that case.

When we bought our "new to us" 2006 F250 we had the same problem. We had been pulling our Layton travel trailer since 1988 with many different vehicles with no issues. When we got our F250 we immediately got the error and no brakes...

Ultimately, after a couple of hours troubleshooting in a blizzard, I found that the polarity of the trailer brakes was reversed. I swapped the polarity in the J-box where the light/brake cable connected to the trailer...No more fault and lots of brakes.

I'm an electrician and I cannot explain why this was so, unless there were surge suppressing diodes in the circuit, but I don't think so?

[Beekeeper]

When we bought our "new to us" 2006 F250 we had the same problem. We had been pulling our Layton travel trailer since 1988 with many different vehicles with no issues. When we got our F250 we immediately got the error and no brakes...

Ultimately, after a couple of hours troubleshooting in a blizzard, I found that the polarity of the trailer brakes was reversed. I swapped the polarity in the J-box where the light/brake cable connected to the trailer...No more fault and lots of brakes.

I'm an electrician and I cannot explain why this was so, unless there were surge suppressing diodes in the circuit, but I don't think so?

At a rally a few days ago, I worked on a new RV that had no breaks. There was a short on the hot side of the brakes. Turned out the factory installed a ground from the frame to the brake magnet wires on the left side of the front axle. Then they hooked up the wires to the trailer connector with that grounded side on the brake pin. Had it been reversed, it would have worked fine.

And, I agree with another comment: Dump the magnets and get electric/over hydraulic disc. Works so much better.

[tthomison]

It took awhile but I finally discovered what my problem was. First, thanks again for all he comments and help that was offered. When I took it in to a different shop, they discovered that when the dealership installed the weight distribution hitch, they installed the clamps that go on the trailer over the brake wires. This grounded out the wires resulting in no breaks. The wires were on the underside of the frame so you couldn't see them. Once they reconnected the wires, I had breaks. Sometimes the simple problems are the most difficult to solve.

[geotex1]

Trailer-side issue. Sounds like someone does not know how to actually troubleshoot trailer brakes. Start at the junction box for the trailer umbilical. Connections are notoriously poor there. Then check the connections at the backing plates. Also notoriously problematic.

[Wileykid]

I have had to fix wiring for the brakes on my trailer. I found several pinched/frayed wires (all near the axle). First thing I would do, is get under the trailer, and start from the plug and trace the wires, looking for obvious issue's. Usually, the fault is not in the brake drum. After that, the multi-meter would come out.

[Viper02]

Two very easy and quick checks to see if RV brakes are working are:
1. with truck disconnected pull emergency brake disconnect pin... RV brakes should all lock up and you can hear a slight hum if you
listen at the hubs of both axles
2. With a multi meter measure on the RV 7 way connector at pins 1 and 2 with MM is OHMS scale... Resistance should read around 1.6ish ohms of resistance

You are measuring thru the RV 7 way plug wiring back to ALL FOUR magnets which are wired in parallel.. if this reading is different then
you will need to remover the two wires on the back side of each brake backing plate and measure the resistance of each Brake magnet

Each one should measure around 3.8 ohms .. if these all read good then your issue is between the RV 7 way plug wiring back to where each
brake magnet wire branches off from the main feed line

[AZMike]

Two very easy and quick checks to see if RV brakes are working are:
1. with truck disconnected pull emergency brake disconnect pin... RV brakes should all lock up and you can hear a slight hum if you
listen at the hubs of both axles
2. With a multi meter measure on the RV 7 way connector at pins 1 and 2 with MM is OHMS scale... Resistance should read around 1.6ish ohms of resistance

You are measuring thru the RV 7 way plug wiring back to ALL FOUR magnets which are wired in parallel.. if this reading is different then
you will need to remover the two wires on the back side of each brake backing plate and measure the resistance of each Brake magnet

Each one should measure around 3.8 ohms .. if these all read good then your issue is between the RV 7 way plug wiring back to where each
brake magnet wire branches off from the main feed line

Just a question - Why would you hear a hum at the hubs? The brake magnets are powered by DC current. If they had AC current going to them, then you should most definitely hear a hum.