Brake Controller - Short

[mnichols]

Hello,

The other day I had some truck problems so a friend had to tow my trailer while my truck was being towed. He has a prodigy brake controller that would show a short and then it would go out. It did this a few time in the 30 minutes he towed my trailer. I then borrowed another friends truck (2013 Dodge with built in controller) to get my trailer home and I had the same issues. The mesaage on the dash would say the trailer was connected then it would show the short and not be connected. Now I have a 2008 Duramax with built in controller and I never seem to have this issue where it shows a short, but there are times when it feels like my trailer brakes aren't working as they should.

Since I just got the trailer home yesterday I haven't had a chance to search yet. Where should I start my search... back by the trailer brakes to see if I lost a ground or maybe a cut wire or check the box where all the trailer wiring connectes to the 7 pin plug wire? I also noticed that running lights etc work fine when connected to my truck but when I turned them on the 2013 Dodge the trailer had no lights, however the brakes did work when it showed the trailer connected. Thanks

[Gdetrailer]

mnichols wrote:
Well I did a quick check under the trailer. I started at the box where the 7 pin plug terminates. Everything looked good there. I then went to the axles. Checked the wires where they go through the axles and pulled a few inches out on each side, wires actually looked good. Where the wires go into the hubs all looked good. I checked where they are sliced at each wheel and two of the wires looked like they got pinched. I'm not sure it was bad enough to cause the issue I'm having but I'll probably redo the splice and replace the wire. Thanks

The wire insulation will chafe most likely in the middle of the tube since the wire will droop down, hence the reason one poster mentioned pulling some of the wire OUT of the tube. In theory this would suspend the wire in mid air inside the tube. This would eliminate the wire from touching the tube but at the same time you are now suspending the wire and that will eventually lead to the wire stretching or breaking.

I meet a lot of resistance on this forum when I tell folks to simply replace the wire and do it correctly instead of messing around and trying to trouble shoot the mess the manufacturers made.

At the same time you will NEED to pull ALL the drums and inspect the magnet wires from the outside right to the magnets. Make sure the magnets are not worn/deteriorated either. If you find a nick in the magnet wires you can generally get away with covering the nicked portion with a piece of heat shrink tubing. Then try routing the wires away from moving parts.

Intermittent problems like this are the most frustrating ones to locate and fix, therefore I state that it is often easier and quicker to rewire it and be done with it.

[Gdetrailer]

enblethen wrote:
SJ cord is rubberized. It is not thermal plastic. Yes there is some other cables that are thermoplastic like the brake cable.
From your link:
All four types (SJ cable, SJO cable, SJOW cable; and SJOOW cable) are considered heavy duty, due to their thermoset rubber jackets

I was REFERRING as "SJ TYPE".

For the record, The "O" designation is OIL/CHEMICAL RESISTANT which means any "S" cable which has the "O" designation is NOT STANDARD RUBBER and can and will be perfectly fine with road salt.

The "W" designation is for WEATHER RESISTANT and that means it is PERFECTLY SUITED FOR USE OUTDOORS AND RAIN/WATER/SNOW/ICE along with SUNSHINE.

Most RETAIL places only CARRY SJOOW so therefore what ever you buy is perfectly fine to use. Even many electrical supply shops do not carry SJ or SJO any more since SJOW and SJOOW basically obsoleted the older designations.

On top of that the outside jacket of SJ type cord is at least 3 times THICKER than any RV brake wire I have removed and not to mention the insulation IS far superior to brake wire.

For the record, the RV "brake wire" I have removed, the outside jacket was hard and brittle and the inside wire insulation CRACKED if I bent it more than 45 degrees. I ripped out a lot of GARBAGE "RV" quality wiring in my last rebuild..

Seen so pretty horrific sights to, found a rats nest of 12V wiring in the wall that had MELTED into a sold mass and nearly melted into the nearby 120V wiring running by it..

The 12V wires insulation CHAFFED and SHORTED as it went through a metal thimble in the stud (thimble is there to prevent screws/nails or staples from damaging the wire). I can't find the photo of that glob right now or I would post it...

Like I stated, your shore cord IS a "SJ" TYPE (could be SJ, SJO, SJOOW or any OTHER "S" designation), there is no way for me to know what the manufacturer used on YOURS) and "SJ" TYPE cordage can and will work fine. Not to mention you can find it at Lowes and Home Depot (Lowes has SJOOW 10ga for around $1.80/ft), pricy? A bit, BUT you get far SUPERIOR jacket that will most likely outlast the trailer.

[mkirsch]

Well if that's the the only thing you've found, it probably *IS* bad enough to cause problems.

[mnichols]

Well I did a quick check under the trailer. I started at the box where the 7 pin plug terminates. Everything looked good there. I then went to the axles. Checked the wires where they go through the axles and pulled a few inches out on each side, wires actually looked good. Where the wires go into the hubs all looked good. I checked where they are sliced at each wheel and two of the wires looked like they got pinched. I'm not sure it was bad enough to cause the issue I'm having but I'll probably redo the splice and replace the wire. Thanks

[enblethen]

SJ cord is rubberized. It is not thermal plastic. Yes there is some other cables that are thermoplastic like the brake cable.
From your link:
All four types (SJ cable, SJO cable, SJOW cable; and SJOOW cable) are considered heavy duty, due to their thermoset rubber jackets

[Gdetrailer]

enblethen wrote:
SJ cord is one of the wire types not too use. It cannot last long with the road salts and chemicals.
This is brake wire.
Brake wire

SJ cord USES the SAME jacket as your trailers power cord and even the trailer to vehicle cable. My trailer is parked beside a busy road and GETS a lot of winter cold along with the salt spray from the road. Trailer is plugged in year round and I have not seen any deterioration of that cord and it is the original cord and at 31 years of age I don't think anyone is going to have a problem using SJ..

That SJ jacket will easily outlast the trailer.

I don't buy into the idea that a wire sold as "RV" wire or "brake wire" is going to last longer. You brake wires ARE out of the sun so UV exposure is not an issue.

[enblethen]

SJ cord is one of the wire types not too use. It cannot last long with the road salts and chemicals.
This is brake wire.
Brake wire

[Gdetrailer]

enblethen wrote:
If you decide to rewire the brake circuit, get proper brake wire. It is two conductor sheathed cable. The sheath protects the conductors from the chaffing.

"SJ" type wire can be used HEREwhich is a heavy duty flexible jacketed cable.

Or do like I did, use flexible plastic conduit and regular stranded building wire (I have "leftovers" from home wiring projects so that is what I used). "SJ" cord, flexible plastic conduit and stranded building wire ALL can be easily found at Home Depot or Lowes.

Using SJ type cord or plastic conduit I do not think that it is necessary to buy "brake wire"..

[enblethen]

If you decide to rewire the brake circuit, get proper brake wire. It is two conductor sheathed cable. The sheath protects the conductors from the chaffing.

[Gdetrailer]

Dave H M wrote:
on the wire that runs thru the axle.

consider giving it a tug from one end and then the other. On my flat bed trailer, that must have moved the chafed wire off the axle and it has been happy for a few years now.

While that might work for a short time it isn't a permanent "fix" and eventually after you put enough tension on the wire inside the tube it will break at the point of entry into the tube.. Most likely will do that at the most inopportune time (like going down a 8% grade hill)..

It is much wiser to fix it right the first time and know it isn't going to give anymore trouble down the road.

[Dave_H_M]

on the wire that runs thru the axle.

consider giving it a tug from one end and then the other. On my flat bed trailer, that must have moved the chafed wire off the axle and it has been happy for a few years now.

[RCMAN46]

If your brake controller can lock the trailer brakes at a setting less than max larger wire will not improve braking performance.

You probably have a wiring problem in the trailer.

[DiskDoctr]

You'd be surprised on what counts as wires on the magnets these days 😞

if you pull your hubs, on one flat trailer I have, two magnets had the wires breaking/broken off the magnet. Maybe they were tangled in the oem brakes, maybe they were junk.

[mnichols]

Thanks for the info.. I'll dig into this over the weekend.