Break-Away Switch

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Scott 3

Scott 3

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Jan 17, 2016
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The cable to my break-away switch has always been a bit long.  The cable droopped underneath my nose jack while I was disconnecting in the dark.  I noticed that my TT was not decoupling as easy as I expected.  I ran the TT up and down and it decoupled.  I noticed that my cable broke.  I pulled the plastic plug for the switch out so I could bend the switch back up.  I left  the plug out figuring that I could inspect it in the daylight.

The break-away switch completely melted and some of the brake wiring burned.  I just about had a fire and didn't know while it was happening.

I spent a lot of time over the past two days replacing wires, connectors, etc.  I hooked up to the TV and the brake controller shows everything is working.

New TT owners should be warned about break-away switches and their limited duty cycle.  In the course of troubleshooting I came across similar stories.  This seemingly innocuous switch can be dangerous to any trailer owner who doesn't realize what can happen if a break-away switch is left engaged too long.
 
Thanks for sharing this OBX,
 
I hadn't even given this scenario a thought.  I do occasionally test my breakaway switch but had no idea that leaving it engaged would cause heating to the point of melting and/or fire.  In your research did find that this is a design flaw with all breakaway switches or a random occurrence?

As far as a lengthy cable, ours was too.  I halved the length to resolve this problem.

Thanks again,

Phil


OBX said:
The cable to my break-away switch has always been a bit long.  The cable droopped underneath my nose jack while I was disconnecting in the dark.  I noticed that my TT was not decoupling as easy as I expected.  I ran the TT up and down and it decoupled.  I noticed that my cable broke.  I pulled the plastic plug for the switch out so I could bend the switch back up.  I left  the plug out figuring that I could inspect it in the daylight.

The break-away switch completely melted and some of the brake wiring burned.  I just about had a fire and didn't know while it was happening.

I spent a lot of time over the past two days replacing wires, connectors, etc.  I hooked up to the TV and the brake controller shows everything is working.

New TT owners should be warned about break-away switches and their limited duty cycle.  In the course of troubleshooting I came across similar stories.  This seemingly innocuous switch can be dangerous to any trailer owner who doesn't realize what can happen if a break-away switch is left engaged too long.
Click to expand...
 
this happened to us on our first camper, went to hitch up and found the break away pin in the driveway and the switch all melted. I replaced the switch and all worked fine- the other day my DW pulled the pin out with her bike- fortunately I was able to put it back in right away

this is good info to share
 
I have a battery disconnect switch with the breakaway switch wired on the side that can be turned off.  I know that I will be hollered at for this, but connecting a circuit without a fuse needs a quick way to disconnect. 
 
Pictures of the burned and melted switch:
 

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Thanks for sharing.

Last year, just prior to winterizing my TT, after I unhooked the break-away cable somehow got hung up on the hitch. and in my haste I didn't see it.  I ended up pulling the plunger as well as breaking the cable when I pulled the TV away.  Fortunately I heard the cable break, and was pulling the battery for winter, so nothing too dramatic occurred, other then another spring fix to the list. ::)
 
Nice thread. What's the best way to test my breakaway switch? My switch cable is wrapped around my tow chains several times. This is how I was told it was done. Is that correct?
 
I test mine by grabbing my breakaway cable and giving it a good yank - it should pull right out.  I do NOT wrap my breakaway cable around one of my tow chains or anything else - that seems like it could interfere with the breakaway system and sequence.  Regarding sequence, below is my understanding of the events/failures that would cause the breakaway system to be needed.

1) Your towed vehicle becomes disconnected from your towing vehicle.  2) The nose of the towed vehicle falls on your tow chains.  3) Your tow chains fail and your towed vehicle has now become free of the towing vehicle.  4) during separation of the towed vehicle the breakaway cable engages the electric brakes on the towed vehicle and is comes to a stop.

Phil
I'm no expert though, so let's see what others say...

goose33 said:
Nice thread. What's the best way to test my breakaway switch? My switch cable is wrapped around my tow chains several times. This is how I was told it was done. Is that correct?
Click to expand...
 
H5-Phil said:
I test mine by grabbing my breakaway cable and giving it a good yank - it should pull right out.  I do NOT wrap my breakaway cable around one of my tow chains or anything else - that seem like it could interfere with the breakaway system and sequence.  Speaking of sequence, below is my understanding of the events/failures that would cause the breakaway system to be needed.

1) Your towed vehicle becomes disconnected from your towing vehicle.  2) The nose of the towed vehicle falls on your tow chains.  3) Your tow chains fail and your towed vehicle has now become free of the towing vehicle.  4) during separation of the towed vehicle the breakaway cable engages the electric brakes on the towed vehicle and is comes to a stop.

Phil
I'm no expert though, so let's see what others say...
Click to expand...

Right or wrong that has always been my understanding.  The break-away cable should engage the brakes only if the towed item becomes completely detached from the TV.
 
Gods Country said:
Right or wrong that has always been my understanding.  The break-away cable should engage the brakes only if the towed item becomes completely detached from the TV.
Click to expand...
yep..this ^^^..is how the break away switch should only work. the trailers brakes WILL NOT engage if the hitch just comes off the ball ?, the trailer has to come off the ball, and completely disconnect from the TV, it will not work if it just comes off the ball, and hangs down on the safety chains. the safety chains just keep it still attached to the TV. once the safety chains fail ?, then the trailer is on its own. when this happens, the break away cable pulls the plastic plug out of the switch, and the on board 12 volt battery that SHOULD BE on the tongue will operate all the electric brakes at all wheels, stopping the trailer from free-rolling down the road.
 
You should also inspect your brake magnets - like the switch, they're not designed to have the full 12 volts on them for extended periods.

A visual inspection is best, it means pulling the brake drums and looking for burnt or melted wiring.  A quick test to see if the magnets are still working is to energize the brakes and pass a compass across the face of the wheel.  A working magnet will strongly deflect the compass.
 
As for the long cable just tie a loose overhand knot in the cable.  Like a big loop.  This takes up the extra length without interfering with function.
 
I should have shortened the cable.  I installed a coiled cable during the switch replacement.
 
Lou Schneider said:
You should also inspect your brake magnets - like the switch, they're not designed to have the full 12 volts on them for extended periods.

A visual inspection is best, it means pulling the brake drums and looking for burnt or melted wiring.  A quick test to see if the magnets are still working is to energize the brakes and pass a compass across the face of the wheel.  A working magnet will strongly deflect the compass.
Click to expand...
Lou,
What would be considered an extended time period?
I'm thinking of a situation like being in heavy traffic on a continual upgrade where you are on the brakes for a fairly long period of time, possibly stopped even, could this cause overheating of the trailer brakes... been in that scenario several times and never gave any thought to TT brakes...
Thanks Lou for bringing it to our attention.
Keith
 
If you have an inertial brake controller, like most of them are these days. You only put high voltage on the brakes if you are actually in the process of slowing down. Other than that, they usually default to the initial setting, which may be about 10% of their total ability.

If you are stopped, or in heavy traffic, and keep your foot on the brake all day long, you are still probably only applying 10% of battery voltage to the trailer brakes. Shouldn't be an issue.

Frank.


Edit: Fixed text size.  -LS
 
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