KATOOM

Mexstan, we posted the same thing at the same exact time.....

Mexstan

Funny. How is that for a coincidence? Two posts from two different people in two countries at the same time with the same info .... that MUST mean that this is solid info. Right?

mini14

Ive had similar probloms with brake controllers driving me nuts. One minute itd fine. Another they dont work. All wiring checked out fine. After pulling the drums id find out 1 or 2 ofvthe magnets were worn down so much they were shorting out the system

RobG

I jacked up one wheel today, then applied 12v (from a fresh RV battery) to the appropriate line at the 7-pin plug, and also to the ground wire. Nada. Wheel still spins freely. I then applied 12v to the running lights and they lit up just fine.

So... whaddaya think? Bad wire to the brakes? I'd hate to have to pull the brakes apart to see if the magnets are shorting (three axles' worth), but I will if I have to.

KATOOM

Still sounds like a loose connection. I'd climb under the trailer and disconnect the main lead line to the first axle. Then connect the battery again to the correct pin and see if that wire is energized. If it is then reconnect to the axle brake wire and so on and so on. Really there isnt much to these brakes. Very simple as its just 12v wire to brake magnets and the controller delivers ramped voltage depending on brake power needed. But they're usually slapped together in such a pish posh manner from the factory that its not uncommon to find weak connections or wires rubbing through due to bad placement.

RobG

Thanks...guess I'll do that here after lunch while the weather is halfway decent. I hope i can find that wire easily enough; my trailer's entire underbelly is covered in that corrugated plastic stuff and I really don't want to have to try to pull it down if I can avoid it.

RobG

Okay, back from that test. So, there are two black wires coming out from behind that plastic covering stuff for each of the three axles, on the left side of the trailer. From there it goes to the brake and then into the axle and across to the other brake.

I cut the first pair of wires and put my meter on them. I get continuity between them, but not between any one of them and ground. Is this normal?

Then I hooked my battery up to the brake line and ground as before. No volts using the same method as above.

Mexstan

Another thing that you could try is to obtain one of those 12v circuit testers with the long, very sharp blade. While those are very useful tools, I have a love/hate relationship with them. Seem like most times that I use that tool, that the sharp point often finds a way to embed itself painfully deep into a finger.

Make sure the ground side of that tester is properly grounded to the RV or run a temporary ground to your truck. Go right to each wheel and push the point of the tester thru the insulation of the positive side of the wire going to the brake. Have someone push on the brakes and see if it lights up. No light means that there is a bad or broken wire between there and your truck. If it lights up, then it could (but not necessarily mean that something is bad inside the drum and the drum needs to come off.

RobG

At this point, I'm seriously considering just running a whole new brake wire from the wiring box on the pin back to the wire running to the axles. Will wait and bit and think it over.

KATOOM

If I understand your test procedure, it sounds like you lose a connection in that main wire to the brakes. What I dont understand is the continuity between them part. One wire is hot and the other is ground unless the hot lead has a bad connection, which would then be one ground, one open.

Have you opened up the junction box at, or just after, the hitch? It should have that main line in there too and possibly tied together with a crimp wing nut. Here's some diagrams to compare against if you're unsure what to look for. https://www.google.com/search?q=trai...w=1366&bih=659

RobG

Yes I've been in the junction box. Things in there "look" fine I guess. I've found the blue wire in there that comes from the truck's trailer brake wire at the plug. I was trying to trace the wires yesterday but it's not really possible short of pulling the filon on the underside of the 5th wheel overhead (which would be a bit PITA). As it is, even running a whole new wire will be a bit of a pain for that same reason.. it'd probably end up having to be external from the pin down to the underside of the trailer.

KATOOM

Pulling the under-lament cover shouldnt be necessary as the wire "shouldnt" be pieced together where you cant see it or reach it. The only junction locations should be at the junction box and the axles.

nkennedy

Your probably seeing continuity thru the magnets on other wheels. Unless they are shorted somewhere else.

Busboy

If the wires from one side of the brakes crosses over through the axle then the axles are most likely Lippert axles, while I'm not that keen on Lippert axles they do the job but I don't like the connectors they use at each brake plus the wires inside the axle can rub through. As your P3 can't see the trailer you don't have continuity so either a broken wire, a bad connection or an open magnet.

Yes that would be normal and proves that that axle is ok.

mini14

ive been replacing trailer brakes for 17 years now..pull the drums and see whats going on in there..magnets and wires don't last forever and its a good idea to grease the bearings..once I over greased an axle nd blew out the inner seals due to using a pneumatic grease gun. ill never do that again.if an inner drum seal leaks,it will coat the shoes with grease and the brakes wont work either.i usually replace my trailer brakes every 2 years wether they need it or not because their so easy to do just time consuming...ive got 2 trailers with electric brakes that I take care of every spring I pull the drums to see whats going on.i replace the drums seals every 2 years with the brakes. best prices and shipping rate from http://www.easternmarine.com/boating...FdKLswodub4Gcw