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Open Roads Forum  >  Tech Issues

 > Trailer Brake issues.....

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js415

Newnan, Georgia

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Posted: 10/12/19 09:33am Link  |  Quote  |  Print  |  Notify Moderator

The existing "home run" wiring is encased in a wire loom from the trailer tongue to the first axle.

This is then completely covered by the coro-plast material that covers the bottom of my trailer. While not impossible, it would be quite a job to replace unless I can pull it out of the wire loom in one whole section while pulling new wire in.

I bought a 100' roll of 12/2 wire. That is what I used for the new wiring at the axles.

I would rather diagnose the problem and fix it, than just start replacing parts. It may come to that though!!

It does not seem like it would be the wiring under the trailer based on the way it is installed.

I did some OHM test this morning. Reading from the trailer connector, I get 1.4-1.5 ohms.

Is this indicative of anything? From other sources I gather 4 brakes should be around .8 ohms.

Does that sound right? Reading through all the wiring, connectors and splices could amount to 1.4OHMS???

Thanks,

Jerry

Gdetrailer

PA

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Posted: 10/12/19 01:19pm Link  |  Quote  |  Print  |  Notify Moderator

12/2 Romex?

If so that is solid wire, not a good choice for this application, you NEED to use STRANDED wire, it will last much longer in any place that the wire is exposed to a lot of flexing (like as the case with trailer brake wiring.

Plastic jacketed 12/2 "SJ" type cord (12/3 SJ could be subbed in, just ignore the third wire) or even 12G speaker wire would be far better choice since they are stranded wire since we are talking Hone Depot or Lowes and they HAVE extremely limit choices in what they carry.

As far as the coroplast goes, simply run the wire on the UNDERSIDE of the coroplast and attach the wire via wire clamps every couple of feet using screws into the clamps into anything wooden or structural you can. Otherwise poke a couple of holes in the coroplast and FISH the wire back (YES, the wire CAN be left unattached, the corroplast will support the wire).

Not sure why coroplast stumps so many people, there IS LOTS of ways to get around this that are not hard or difficult.

Finally, Ohming it does not give an accurate picture at extremely low resistances you are working with. Standard ohm meters are not accurate, takes a resistance bridge to get an accurate reading.

Much better to use an ammeter and a 12V source (if you use a separate battery or power supply make sure you use a 15A fuse max), with a 12V battery you should get pretty close to 11.5A-12A for four brake magnets.. Get much less than that and you have a lot of bad connections.

MORE the 12A and you have a short somewhere..

However, you ARE dealing with an intermittent problem, ohming it or even using a battery/ammeter reading are not going to be helpful since you are in a static non moving situation.

Troubleshooting intermittent problems often REQUIRES SUBSTITUTING WITH KNOWN GOOD PARTS. In this case subbing in all new wire along with all new wiring terminations will not cause any harm but it WILL drastically shorten the time you will spend trying to hack the wiring up and troubleshooting one item at a time like you are doing..

The highly intermittent issue IS the reason to simply scrap the cheap junky OEM wiring and move on with new (KNOWN GOOD) better wiring.

time2roll

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Posted: 10/12/19 02:16pm Link  |  Quote  |  Print  |  Notify Moderator

js415 wrote:

time2roll wrote:

Grab your clamp-on DC ammeter and check each wheel is getting about 3 amps when controller is applied manually. Then reconcile with the amps coming out of the controller.
No meter? Good excuse to buy a new tool [emoticon]


I'm not sure that will work. I can sometimes drive 20-30 minutes without the error message. Then sometimes I pull over to an exit ramp and it does it all the way up the ramp.

With it being intermittent, would a amp meter reading tell me anything conclusive?
Probably not. Can only detect a fault while it is happening.

Could indicate the fault while you jiggle the wires looking for a short. No guaranty.


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drsteve

Michigan

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Posted: 10/13/19 08:05am Link  |  Quote  |  Print  |  Notify Moderator

Went to a NSRA hot rod show and swap meet recently, noticed that several of the vendors had spools of 10/2 stranded wire for about what Lowes/HD charge for regular stranded 10/1 wire.


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Vette Racer

Oklahoma

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Posted: 10/13/19 11:02am Link  |  Quote  |  Print  |  Notify Moderator

Narrow it down to which axle, then to which side. At that point pull wheel and look for chafed wires going to the magnet. Almost every time I've seen this it ends up being the magnet wires rubbing against the actuator lever inside the drum. Of course this assumes that you have drum brakes!


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js415

Newnan, Georgia

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Posted: 10/13/19 12:03pm Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:

12/2 Romex?

If so that is solid wire, not a good choice for this application, you NEED to use STRANDED wire, it will last much longer in any place that the wire is exposed to a lot of flexing (like as the case with trailer brake wiring.

Plastic jacketed 12/2 "SJ" type cord (12/3 SJ could be subbed in, just ignore the third wire) or even 12G speaker wire would be far better choice since they are stranded wire since we are talking Hone Depot or Lowes and they HAVE extremely limit choices in what they carry.

As far as the coroplast goes, simply run the wire on the UNDERSIDE of the coroplast and attach the wire via wire clamps every couple of feet using screws into the clamps into anything wooden or structural you can. Otherwise poke a couple of holes in the coroplast and FISH the wire back (YES, the wire CAN be left unattached, the corroplast will support the wire).

Not sure why coroplast stumps so many people, there IS LOTS of ways to get around this that are not hard or difficult.

Finally, Ohming it does not give an accurate picture at extremely low resistances you are working with. Standard ohm meters are not accurate, takes a resistance bridge to get an accurate reading.

Much better to use an ammeter and a 12V source (if you use a separate battery or power supply make sure you use a 15A fuse max), with a 12V battery you should get pretty close to 11.5A-12A for four brake magnets.. Get much less than that and you have a lot of bad connections.

MORE the 12A and you have a short somewhere..

However, you ARE dealing with an intermittent problem, ohming it or even using a battery/ammeter reading are not going to be helpful since you are in a static non moving situation.

Troubleshooting intermittent problems often REQUIRES SUBSTITUTING WITH KNOWN GOOD PARTS. In this case subbing in all new wire along with all new wiring terminations will not cause any harm but it WILL drastically shorten the time you will spend trying to hack the wiring up and troubleshooting one item at a time like you are doing..

The highly intermittent issue IS the reason to simply scrap the cheap junky OEM wiring and move on with new (KNOWN GOOD) better wiring.


Not Romex. Regular 12/2 stranded...

I install Structured cabling systems for a living, so I'm used to fishing and winding cables around a bunch of weird places and situations.

I just don't want to start replacing stuff until I find the actual problem.

Thanks for your advice,

Traveling with the trailer in 2 days, so I will be able to do a lot of troubleshooting.

Jerry

js415

Newnan, Georgia

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Posted: 10/13/19 12:04pm Link  |  Quote  |  Print  |  Notify Moderator

Vette Racer wrote:

Narrow it down to which axle, then to which side. At that point pull wheel and look for chafed wires going to the magnet. Almost every time I've seen this it ends up being the magnet wires rubbing against the actuator lever inside the drum. Of course this assumes that you have drum brakes!


This is exactly my plan right now. It might take a little bit longer, but it will be good time spent.

I can isolate the problem and then repair it.

Thanks,

Jerry

js415

Newnan, Georgia

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Posted: 10/22/19 05:04pm Link  |  Quote  |  Print  |  Notify Moderator

UPDATE FROM THIS WEEKEND.....

We headed out Thursday morning for our trip. I never even made it out of the driveway before I started getting the "OL" signal, and then it went to a constant "SH" signal.

This was good because it would give me an opportunity to trace it down while the brakes were not functioning correctly.

I crawled under the trailer and pushed, pulled, and yanked on every set of brake wires I could find. Nothing stopped the "SH" condition.

I followed my plan and cut away the rear axle feed line. As soon as it was cut, the "SH" went away, and the rest of our trip out and back was perfect.

Good brakes the whole time. So now I know it's on the rear axle, and since I have replaced all that wiring, it must be inside one of the hubs. Time to take them off and do some inspection I guess.

Thanks,

Jerry

Weldon

Texas

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Posted: 10/22/19 06:42pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks for the follow up Jerry.

Lynnmor

Red Lion

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Posted: 10/23/19 06:31am Link  |  Quote  |  Print  |  Notify Moderator

js415 wrote:



I followed my plan and cut away the rear axle feed line. As soon as it was cut, the "SH" went away, and the rest of our trip out and back was perfect.

Good brakes the whole time. So now I know it's on the rear axle, and since I have replaced all that wiring, it must be inside one of the hubs. Time to take them off and do some inspection I guess.

Thanks,

Jerry


You cut a wire and then had good brakes?

If the problem was in a "hub", how did you have good brakes?

My guess is that you have a short inside an axle.





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