Wiring for Brakes

[Rhoadzie]

I have had a couple of issues with brakes and frankly am not sure about the wiring.

Long story. Last year on my way to Arkansas, I lost trailer connection but all the lights were working. I realized that it was loss of connection at the brakes. I traced the wire to the front set of brakes and reconnected. the broken wire. Easy. But I have never thought the brakes were doing what they should. I could never get them to all lock up even with full gain on my factory brake controller. The front set will lock up but not the other two axles/

Fast forward to this year, I had to replace my rotors and brakes on my truck. They seem to be doing all the work. When going through the mountains I again noticed I just don't have much brake. SO, I climb under my Voltage 3970 Fifth wheel and notice two sets of wires hanging down by each of the rear two axles. They really look like they have never been hooked up. Can any body show or explain what the wiring is supposed to look like. I have some pictures, but I am not sure you can tell since it is not very light in the picture. Hopefully they will upload.

[Rhoadzie]

OK, let me try to explain what I think is happening. I have two wire connections with three wires at every axle.Two wires come out of the underbelly in each connection and the third wire of every connection is not hooked to anything. Then I have two other sets of connections at each hub with two wires coming out, one goes to the brake on that side and the other goes in the axle then I assume to the brake on the other wheel on that axle.

However, On the front set of brakes I do NOT have a wire hanging down and it is connected to the connections going to the brakes and into the axle. (I am not sure this is making sense to anyone.)

I really don't think I have power wired to any of the rear brakes and it looks like they never have been wired. I bought this fifth wheel last year used. Can any experienced RV brake guys out there help me with this trouble shooting?

[ArmyVeteran]

WOW! Im sure this will be a very interesting discussion. I am not a TT expert. But, if all three axles have electric brakes. Then all the wiring should be the same. It would seem to me that your other two axles brakes are not hooked up.



Good luck.

[ArmyVeteran]

Or not 😎

[KN5DX]

My suggestion for correcting the problem : Start by troubleshooting from scratch. There appears to be multiple problems. Some may just be a wear n tear, others damage, etc.
So first step would be get the axle manual from Lipert (find sticker on your axle to confirm). This will give the info as to how the electric drums are working and likely standard wiring configurations. Get a pad and draw out how it's wired as you inspect each axle. If you have a clamp on multi-meter use to measure current as applied from TV before any repairs and after. I don't think there is going to be a quick fix here.

[sundancer 87]

My clamp on meter only measure AC current when using the clamp on function.

[acdii]

Easy test would be to jack up each wheel and set the breakaway. If the wheel locks, it has brakes, of not, then tear it down and find out why.



In simple terms, there is the power 12v to the magnet, and from the magnet a ground wire. The front axle may be single homed, meaning one wire powering just that axle, and the two trailing axles split wired, where one wire splits off to both axles.





See below.





If no braking on the trailing axles, then get a trouble light, or multimeter, and tap each wire to see if 12V is present when the breakaway is engaged. Do this at each wheel. If 12V is present, tear down the hub and find out why, if no 12V then back trace or run new wires.

[ArmyVeteran]

Originally Posted by KN5DX

My suggestion for correcting the problem : Start by troubleshooting from scratch. There appears to be multiple problems. Some may just be a wear n tear, others damage, etc.
So first step would be get the axle manual from Lipert (find sticker on your axle to confirm). This will give the info as to how the electric drums are working and likely standard wiring configurations. Get a pad and draw out how it's wired as you inspect each axle. If you have a clamp on multi-meter use to measure current as applied from TV before any repairs and after. I don't think there is going to be a quick fix here.

73 to you 😎

[KN5DX]

Poster acdii has some good suggestions. I do want to clarify the comment about looking for 12v. You may or may not see 12 vdc. You TV is actually controlling the amount of current, the voltage could be within a range of say 1-12. The more current applied (brake magnet) the "stronger" it becomes. The breakaway is good idea. This does troubleshoot one side of the circuit (internal to batteries). Do test from TV also so to rule out confirm its not TV or controller. That's part of why my initial suggestion was very high level, and drill down. #1 Rule of troubleshooting visual inspection (you did that). #2 ROT is divide and conquer. This is not going to be easy or quick.

[KN5DX]

Here is what a typical trailer brake control system should look like.

[acdii]

Originally Posted by KN5DX

Poster acdii has some good suggestions. I do want to clarify the comment about looking for 12v. You may or may not see 12 vdc. You TV is actually controlling the amount of current, the voltage could be within a range of say 1-12. The more current applied (brake magnet) the "stronger" it becomes. The breakaway is good idea. This does troubleshoot one side of the circuit (internal to batteries). Do test from TV also so to rule out confirm its not TV or controller. That's part of why my initial suggestion was very high level, and drill down. #1 Rule of troubleshooting visual inspection (you did that). #2 ROT is divide and conquer. This is not going to be easy or quick.

Correct. Depending on the TV, if it is a Smart controller it won't be applying very much to the brakes, and it would have to be hooked up to do this. Using the breakaway gives full power to all the brakes and eliminates the TV at the same time. If all the brakes engage with the breakaway it will reduce the amount of time needed to trouble shoot.


There is an easy way to test all 6 brakes at once. Hook up the truck but not the 7 pin, engage the breakaway and drag the trailer with someone watching the wheels. If there is an issue with wiring, only the locked wheels will drag.

[persistent]

Be careful how long you leave the breakaway active. A full 12 volts on the electro magnets for too long may smoke them.