Trailer brakes not working

LuckyJ

Hello to all.

I might be pretty handy with a lot of things, but trailer brakes are a new thing to me, and even with internet and forum search, I did not found what I am looking for.

So here it is.i found out not to long ago that my trailer brakes are not working anymore. And that is with 2 different tv and controller.
I first tried adjustment, witch they needed anyway, but no better. I was short on time with to many project, and new I was rigging a second TV with a new brake controller. And no better. So I started looking for wire continuity on my tv connector receiver, and double check, all is good, including variable current with manual switch on brake comtroller.

Open the TD rellay box, check every connection, even to the point of diconnecting every thing and reconnecting one by one. I have to admit that I sarted seeing weird thing on my trailer lights and realized that on a last trip with heavy gravel, even if short distance (10 miles), had broken my recerse light wirring and was creating a short. So I diconnected the yellow line going to those. But gremlins are fixed, but still no brakes. Current reach the junction box and varry in intensity, but nothing beyond.

Now, my questions.
Did I mist a fused on the trailer for those brakes?
I have visualy checked the wires to each magnet and they look very good.
If one magnet goes bad, will it cancel the operation of the other magnet?
I have check the braking movement inside the drums, and everything is moving.

I have not open any wire yet, since everything is all sealed and tight. I guess it will be my next step.

Any info is welcome.

I could go to the dealer, but since I am at work until sunday and them heading south to Florida and back, will not make it to the dealer for a full month.

Verna

@LuckyJ, please double-check each crimp on the wiring in the splice box under the front of your T@G. Plus any others you may find.

I have no idea how the brakes work (may I plead blonde hair here?!), but since they are electric and I have personally seen some bad wire splices lately, that might be a place to do some double checking.

LuckyJ

@Verna said:
@LuckyJ, please double-check each crimp on the wiring in the splice box under the front of your T@G. Plus any others you may find.

I have no idea how the brakes work (may I plead blonde hair here?!), but since they are electric and I have personally seen some bad wire splices lately, that might be a place to do some double checking.

Hello Verna. Thank you for your input. But I already did it when I leteraly pull every single wire from the junction box. When I trouble shoot stuff like that, I tend to start at the basic and try to understand each step. But hey, before I lost most of my air, I was also a blond. So I might check them again' just to make sure.

Fishermanandy

Did you check for a good solid ground return to the TV's battery? Lights will work and a ohm meter will show connectivity with a ground through the hitch, while brakes may not work because of the current flow requirements.

LuckyJ

@Fishermanandy said:
Did you check for a good solid ground return to the TV's battery? Lights will work and a ohm meter will show connectivity with a ground through the hitch, while brakes may not work because of the current flow requirements.

Well, I did re checked all the connection in the junction box including ground. I have also reluctantly decide to poke in the magnet wires just a few inch from the magnet on the positive and negative lead and I have currents continuaty, and very good one with power coming from the brake controler. And I have test negative and positive from the junction box on both side. I also now know that one brake can be down and the other can work.

As for trailer ground, I do not think the the ground for the magnet is taken from the frame, but from the wire, since 2 wires are goind from the junction box to each magnet and one is ground(negative) and the other is power (positive).

And the brake controler give me no feed back at all when the trailer plug is connected, only if I jump it with a 12 volts lamp test either at the junction box or the brake wire before the magnet. I will try to test the resistance (ohms) in the magnet to orrow. I am still learning, but I think I am begining to understand how they work.

Still ipen to ideas and suggestions.

LuckyJ

Btw, anybody knows what parts number the magnets have? No info on this in our docs even the ones from dexter.

LuckyJ

Ok, so this afternoon, I decided to cut the wires of one brake magnet. Well, not continuity at all. Tried it also with a motorcyle battery, was easier to bring under the trailer and no current going around that small loop.

I will have two magnets waiting for me at a cousin's place in Ossining NY and will operate this sick trailer. Until then, brakes are brand new on my TV and brake performance is really nice with 4 ventilated good size disk on it.

WilliamA

It looks like I'm way behind on my forums! I've been working on a number of projects and also sneaking off pretty much daily with trailer in tow looking for the Bass hotspots. I'm happy to report that the bass are biting and fishing has been good.

Luc,
It sounds like you've done due diligence on your troubleshooting. This is one of the areas of electric troubleshooting when you need to do both a voltage and a continuity test. I'll get to that. Before I forget, here's the Dexter electric brake maintenance guide:
https://www.dexteraxle.com/docs/default-source/default-document-library/light-duty-electric-brakesc67a839d2ba463c18d7aff64007a4014.pdf?sfvrsn=0
Here's a few tips on checking electric brakes:

First, you need to sort electric brakes out into mechanical and electrical. It's been my experience that most of the problems tend to come from the electrical side. Since you said that you don't have any controller response until you jump it at the tow vehicle connector with a test light, we can assume that the controller is working. If you plug in a test lamp (NOT A JUMPER WIRE OR MULTIMETER) at the trailer harness plug (TV side) brake to ground and get a response (ready) light on the brake controller, we can forget about that for now.

The best, first way to test brake electro-magnets is to check continuity on the trailer side. Test for ohms from the trailer-side brake wire to the trailer-side ground wire. Depending upon what the resistance value of the pucks (magnets) is, you should get pretty close to 0 ohms. As long as you get any reading other than infinity, you can assume you have at least one good puck (magnet). The pucks are wired in parallel so if one is bad (open) you should still get a reading of some continuity value. I doubt you have one bad puck because if only one brake is working, you can usually tell. When trailer brakes are applied with only one side working you'll certainly feel the trailer want to pull the back of the TV in one direction or the other! In addition, if even one electromagnet is working, you'll still get a good ready light on the controller.

I suppose it's a good time to expound on how electric brakes work. They are amazingly simple in principle and nearly bulletproof in practice.
The "pucks" (electromagnets) I refer to are just that; an iron core with electrical wire wrapped around it. There are two wires, one hot and one ground. Many "pucks" have the same color wire coming off both sides; either white/white, black/black or black/red. To the best of my knowledge, it makes no difference which is which. They simply run a current through a wrap of wire that induces a magnetic field into the iron core. When the iron core is magnetized, it sticks to the side of the inside of the brake drum. Usually at the bottom of the drum. As the drum rotates, the magnet drags on the drum, pulling on a lever that applies the brakes. The more voltage, the more magnetism. The more magnetism, the more braking force is applied to the shoes. The same principle applies whether the trailer is going forward or back. Think of a pendulum hanging inside the brake drum that sticks to the side of the drum when voltage is applied.
The brake controller is nothing more in theory than a variable rheostat. You can adjust the maximum voltage with a sliding lever. Usually, if you adjust it to maximum, the brakes will lock up. Most of us set our brake controllers at 2 or 3 bars which works out to about 6-8 volts or so. Every trailer is different so don't look for any specific voltage. Just make sure that when testing your brake system at the trailer plug (tow vehicle side) the voltage goes up and down as you move the slider. A test light will get brighter and dimmer. Many controllers have a separate slider that controls delay. All that does is delay when the brakes are applied, not how much power they get. You want your trailer brakes to come in about the same time as your tow vehicle brakes or just a tiny bit sooner.
That's it. The brakes are as simple a circuit as a taillight circuit. You have two wires (red and black or positive and negative), and a load. That's the theory.

So if you have no "ready" light on the controller, you can be sure that you have an open circuit on either the hot wire, ground wire or the pucks. The pucks do burn out but it's rare and unheard of for both of them to burn out at exactly the same time. Here's the checklist I'd use to test mine:
1. On the trailer plug, test for continuity from the trailer brake wire to the ground wire. If it is infinity (no reading on the meter) than you have an open circuit on the hot wire or the ground wire or the pucks.
2. On the tow vehicle trailer connector, check again to make sure you have a "ready" light when you plug a test light (NOT A JUMPER WIRE!) across between the trailer brake (not brake light!) circuit and the trailer connector ground circuit. If you have a "ready" light on the controller when the test light is connected, check that the light gets brighter and dimmer as you set the power level on the controller up and down. You need a test light to do this, not a multimeter. A multimeter may not have enough current interference (resistance) to trigger the ready light.
3. Check the connector. Often times, I've found that the trailer plug itself is the culprit. You can coax the blades of the trailer-side connector shut with a small screwdriver by prying against the side of the plug.
4. It must be one of those three things: The TV wiring (unlikely in this case as it sounds like you've checked that), the trailer wiring, (more likely) or the trailer plug connector (most likely).

On the mechanical side (and as I've mentioned, it doesn't sound like a mechanical problem) the most common reason electric brakes fail mechanically are:
1. Grease on either the brake shoes or the puck friction material. If there's grease in there, you could apply 13.2 gigawatts of power to the pucks and it wouldn't make any difference. They'd just smoke.
2. Worn brake shoes. Adjust or replace as necessary.
3. Worn pucks. The pucks (electromagnets) do wear out. They either act directly, metal to metal on the side of the brake drum or have some sort of friction material glued to the contact face. Either way, they do wear out, but it takes awhile. If you replace one, replace both or you'll get uneven brake activation because one puck will have different friction coefficient than the other at the same voltage value.

In my humble opinion, the best way to check for voltage across the two wires that go to the brakes is to add a test plug in each wire close to the axle. The two wires travel along the frame to the axle where they split and go out to each wheel. Put a test plug into each wire right before it splits. You can check for both voltage, resistance and amperage there.

Last (and probably should be done first), replace the cheesy crimp-on connectors at the inside of the drums and anywhere else in the circuit you find them with proper, crimp-on/heat-shrink connectors. This circuit pulls a lot (relative term) of amperage. It's in the neighborhood of 5-8 amps at full power. Any connector that is subject to water or moisture infiltration is just a smoke-test (bad thing) waiting for an opportunity.

Let me know what you find.

The part numbers for the pucks (electromagnets) can be found on Dexter's website. I'd list them but they are assigned by axle serial number. I'd be surprised if they were any different than the generic pucks hanging on the wall in most auto parts stores, but you never know...

WilliamA

WilliamA

Luc,
Here's the part number callout from Dexter for magnets:
https://www.dexteraxle.com/docs/default-source/default-document-library/light-duty-replacement-parts-kitsee7a839d2ba463c18d7aff64007a4014.pdf?sfvrsn=0
WilliamA

Michigan_Mike

William, great write-up and this is one of them discussions that I will add t my favorites for future reference material. Thanks for taking the time to do so as I'm sure it will be beneficial to others in the future!

One other request for you as Luc has stated something here (that many are not familiar with the electric brake system) that I believe is spot on and if you are willing, this will help others as well. I agree with your assessment that these systems are probably simple electrically, but since they require time to disassemble and are not easily visible they are somewhat of a mystery and the majority of folks (including myself) are not familiar with electric breaks, nor do people understand how to adjust them, etc.

Would you be willing to do a write-up some time and provide some detail as to how to adjust and test the electric trailer brakes? I'd love to tackle adjusting these brakes myself and am certain that others would like to know more as well. I understand that time is limited, but if in your spare time you could put something together (pics would be a bonus obviously!) in this area we would be very appreciative!

Thanks!

LuckyJ

@WilliamA wow, ok, thank you!

So I have read all the points you have mentionned, And I did all that, from lamp test, to continuity, to ohms. It might have been a bit different,but this is what I did. So I am down to the magnets. I am at work until I leave sunday and all parts store that would have trailer parts are close. Magnet were order from amazon, since My cousin could not find any in the parts store he went to or usualy goes for his buisiness.

He shouls be getting them today and we will work into that moday when we stop by for the night. Are for the wire crimp, I can only agree with you. The heat shrink is not even lined with hot melt glue to seal the connection. I will also take care of that at the same time.

Again, thank you, I will keep you posted.

WilliamA

Mike,
I would be happy to do so. I need to do a major brake adjustment and inspection as well as wheel bearing service so I'll write up a primer on brake testing/maintenance when I do. My trailer just rolled past 45,000 miles on the odometer so maintenance is in order... (yes, I keep a log of my trailer miles.)
WilliamA

LuckyJ

Very good on the trailer log. I think I will try to do so as well, but I did mist the first 4000 km. It will not be on tye book.

Now, and up to date about the magnet. Well, they were bothe dead. Once they were off the axle, we tested them with a 12 volt battery, and nothing, no grab. So we open tha package of a new one, and it grabed a tool we had on hand. So both magnet are now new. And they were not wornout, just dead.

So, you now see a very happy camper, or should I say, traveler! We also mannage to fix my car ac, an other plus! Yepi.

WilliamA

Luc,
It's unusual that both would be dead but certainly not unheard of as that's what you found! Are they worn on the friction face? Often, when they wear they'll get quite rounded. I don't know what actually causes them to fail (go to open circuits) electrically, but I suspect they are pulling too much amperage. Unusual wear patterns on the friction face might be a sign that they are pulling too hard. The lion's share of my experience with e-brakes has been on the 10 inch jobs on my car haulers. It's a given that the smaller diameter drums need more power as they don't have as much mechanical advanntage as the larger ones. In any case, record the resistance reading for the new ones so in the future you can quickly check them with a multimeter. Good reference material to have handy. I think I'll check mine just for reference. They've got a lot of miles on them.
WilliamA

LuckyJ

Ok, just getting back on the web after my 3 weeks of from work and finally 2 weeks down to florida. It was hot and moggy, but no bugs at the Walt disney fort wilderness campground. So all good.

As for the magnet, they were both dead. Might have been related to the reverse light I have installed. I did use small button led lights, and the wire were so small that they broke and started rubbing on the frame and were creating all kinds of gremlins and probably burned the magnet. Replace them, and they have been working realy well for the entire trip.

But I am still not able to set them up like every ine say they should, just below lockup. They have simply never lock, even fron new.

But they work As I want them.

WilliamA

i·ro·ny1
ˈīrənē/Submit
noun
a state of affairs or an event that seems deliberately contrary to what one expects and is often amusing as a result.

After all the banter about brakes of late, I was going up north for the weekend and....wait for it....my trailer brakes went out....

Here's what happened:
Symptom: when I hit the brakes, I get a moment of brakes, then the controller started flashing a red light. According to my brake controller cheat sheet, that meant a direct short somewhere. I finished my 200 mile trip and got back, then peeled off the drums. Things looked fine, so I plugged the drums back on and hooked up the umbilical. As long as I didn't turn the drums (trailer on jackstands, tires off) the controller showed two green bars. As soon as I turned the left drum with brakes applied, I'd get the red flashing light. I pulled that drum back off and cut the wire for the brake magnet. Checked with multimeter and it read 0 ohms. Direct short. I ran down to the local trailer supply joint and got two new magnets, got back and installed the left one. Before I hooked it up, I checked it for continuity and got 17 ohms. Excellent. Hooked everything up and tested...fine and good. No problems. I bought 2 and might get around to replacing the right side one or just wait until I next have the drum off for wheel bearing maintenance.
The bad:

and the good:

It's hard to say what the average ohm reading is from just one sample, but the magnets (per Dexter) pull 2.5 amps so 17 ohms sounds about right. In any case, 0 ohms or infinity is a safe bet for a dud.

I paid $33 bucks a piece for them. My trailer has about 40,000 miles or so. Brake shoes look fine so I left them right where they are.

Some days.....some days......

Gotta be ready for northwestern Nebraska in mid-November, not to mention next week I'll be bass fishing for 3 days in northern Wi.

WilliamA

Michigan_Mike

Good stuff William, thanks for sharing!

Chalkman

Thanks for an awesome thread here. Followed all of the above suggestions on our 2018 XL boondock that we've had for about 10 months. Ruled out issues on TV (2013 Outback), Brake Controller (Curt Echo) and ensured continuity on all wires. Had to dig deeper as all was good with the above. Took the drum off the drivers' side wheel and the magnet literally fell onto the floor. Took the other wheel off and the one of the wires was snapped. Neither of the magnets had the retaining clip fitted.

Pics posted below. I placed the magnet back on just for the pic

Chalkman