Bear with me. Last year coming through WV my truck and trailer brakes got very hot and we had quite the scare. The brakes on the truck got repaired and now onto the trailer. The trailer has 2 axles. It only had brakes on one axle. The rear axle has flanges for backing plates, so I added brakes to the other axle. I rewired both axles with 12 gauge trailer brake wire. The front axle wires come down the left side and piggybacks from left to right. The rear goes down the right and piggybacks from right to left. It is all brought together up front in a junction box. You also have an emergency brake battery on board the trailer. Battery power and ground enter the junction box from the truck (along with all others). Power is jumped to a mini charger for the E brake battery. One wire to the positive of the trailer battery, one to positive from the truck and the other goes to the breakaway switch. From the breakaway switch to the brakes. I got the brakes done and went to burn them in. BARELY any brakes. I turned up the brake control and I have nothing but the left front locking. Back home, I checked all wires and connections. Good. I jacked up the trailer and pulled the breakaway. Nothing but left front, and not fully locking at that. Truck connected or disconnected. I disconnected the trailer battery and tested it. 12.86V. I'll skip a few steps here, I ended up putting my jump box in place of the trailer battery. Truck still disconnected. Pull the breakaway, and I have all 4 brakes. Put the breakaway back in, hook the wire back to the truck and hit the brake control, all 4 brakes. Trailer disconnected, or connected I still have power and ground at the trailer connector on the truck. Which powers the charger for the mini battery. I have power to the charger, and it has a working output for the battery. Everything is working. Except for the battery that still has almost 13V, that I replaced with my jumpbox. I went to the store in utter disbelief. Bought a battery, put it in and the brakes work. I just don't understand. How does the EMERGENCY brake battery play any role in whether or not the applied brakes work? It works, so I'm happy. But I need to understand this. What the heck is going on here. Is this common knowledge and I'm a big dummy? 😆
Electric trailer brakes (drum)
Kefsn
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Agreed. Only response I have to that is the LF run is the shortest run. Maybe the LF used up all the available current??? No different than when half your lights work when there is a ground issue. Not positive, just guessing here. 😆
1955 210 two door post, six cylinder, three on a tree, Navajo Tan and India Ivory
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If the signal was getting to the trailer then you would think that the problem was within the trailer. However, if the signal was too weak to pull in the brakes (meaning low voltage, which could be a ground problem) it is possible that only one or two of the solenoids might be powered enough to overcome the springs. All four of the brakes might have been getting voltage but only the one with the weakest springs or the strongest coil was responding. If there was a large resistance in the system it would have drained off power leaving less for the brakes. The battery could be 12 volts, the resistance causing a voltage drop, and the remaining voltage not being sufficient to activate the brakes. On my trailer, all of the brake solenoids are grounded locally. The problem would have had to have been between the battery and the brakes. It could have been corrosion, either at the battery terminals or at a connection like where the hot wire connects to the terminal strip, or a problem between the trailer and the controller or the controller itself. A loose connection (hot or ground) will cause problems.
It didn't work, then it did. It is intermittent. He needs to go over all the wiring from head to toe. Pull the wire hard at every crimp. If one comes loose, fix it and move on to the next connection. Test every single connection. Every wire. If the brakes are all joined at one point, scrutinize that junction.
Exactly what I did. Which is how I found the loose ground.
I'm sorry, I thought I read in your first post that your jump pack, or a new battery fixed it.
Glad to hear it's working.
I'm just curious, what are you going to be towing?
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Power is looking for easiest path to ground. So if one was working then other 3 may have not had good ground via the springs and frame. The ground to brakes is just for direct path to ground vs the brakes trying to ground through the spring bolts and frame itself.
1955 210 two door post, six cylinder, three on a tree, Navajo Tan and India Ivory
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3,823 Posts
If the frame is not connected to the ground wire in your plug then current has to find it's way through trailer components and the hitch and that is not good. You can't have too many grounds. With my trailer, the ground wire at the bumper socket was grounded to the truck frame but there was no continuity between it and the ground wire in the factory connector in the dash. How that was possible I may never know, but I spliced in a ground wire from the dash connector to the steel in the dash and everything started working. The truck did not come with a factory controller but the wiring harness was there. All fuses related to it were good. I worked around PLCs and control wiring in industrial equipment and it is usually quite straight forward. Automotive electronics confuses the heck out of me, especially Ford.
Unless you are working with audio.
I know, I know. We aren't talking about audio. Just thought I'd be a smart ass.
1955 210 two door post, six cylinder, three on a tree, Navajo Tan and India Ivory
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3,823 Posts
What were your grounds for doing that?
LOL!
Just because I could.
1955 210 two door post, six cylinder, three on a tree, Navajo Tan and India Ivory
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3,823 Posts
good enough!
Yes, you did read that. You were not mistaken. But we all know that the battery didn't "fix" it. Hints the reason for the original post. To help figure out whats still wrong with it. I know the battery didn't fix it. I've already put the old one back in and they still work. So it wasn't the battery. Coincidence I bumped some other wires in the process. Yes.
I had the truck aligned today, so no trailer. I am going to drag it around a few days and see what comes of it. I will also be adding a few star washers, as there is none.
I haul A LOT of appliances for about 23 apartment complexes. So normally it's only loaded with fridges and stoves, etc. So the brakes (to me) were never an issue. The truck has that all day. But for the concern, my '57 sport sedan is going on it to travel to BG. Through WV. So, brakes are a definite.
This is everything here. That is when I bought it in '22 in BG. There's a really cool story behind this car. But that takes a sittin. The trailer since has been painted and re-decked.
Adding star washers is a very good idea. If you can find them, there are good ones that are hardened steel and there are crappy star washers that are soft. The good ones are normally black, not shiny. It's harder to find the small ones like you need that are good. You may have to order them. If you are using the crappy ones, be extra sure to remove the paint from the frame for a good connection. Using electrical grease is also a good idea for longevity. You can use "light bulb grease" from an auto parts store.
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light bulb greas IS di-electric grease in a little expensive envelope LOL.
Yes, I went blank and couldn't think of the name, and an alternative name if he couldn't find the di-electric grease, I added the bulb grease.
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2 bucks for .14 oz or 10 bucks for pretty much a lifetime supply LOL
I actually went through with my IPA trailer terminal cleaners last night too. Rubbed them down with DeoxIT, wiped the excess and then dielectric greased the crap out of them. LOL! I will check on the washers I bought. Thanks for the heads up. I worked at the big F for a while. According to them, dielectric and electrical grease are different. LOL! Not trying to stir the pot! Just showing y'all the mess they sell! I can tell you this, their electrical grease has a very low melting point. I don't like it.
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