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Old 09-04-2010, 12:38 PM   #1
pbahlin
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M.O.C. #9380
Check Your Breakaway Switch

I had one of those experiences where I did something stupid that turned out to be a good thing. It's made me think of something we all should do for safety.

Two days ago I finished a 300 mile tow. It was raining hard when we got to camp and started setting up. I have a Trailer Saver Hitch and part of the decoupling process is to let the air out before you unhook. To save time, as I was leaning into my truck letting the air out, I grabbed the lanyard to the breakaway switch and gave it a yank. Normally I unhook it from the truck and leave it 'connected'. This time, I wanted to get the heck out of the rain so rather than mess around I just pulled it.

My trailer was still connected through the cable to the truck. This meant that my trailer brakes got applied for the few minutes it took me to get to the back of the truck and disconnect the cable. No big deal right?

Well today I was putting things back together and discovered a melted breakaway switch! It was so messed up that the breakaway insert would not go into the switch. In the process of trying to figure out what had happened I gave a little tug to the wires on the switch. One of them came right out and the copper was totally green from the insulation all the way to the end of the wire. This tells me it had never been a good connection, probably never properly crimped inside the sealed switch.

As near as I can figure, the bad connection got hot for the first time in its life and the switch was toasted. My brake circuit still has about 1.6 ohms at the connector and I'm told by an RV service tech that this is what you should see in a normal circuit. I'll be checking my brakes before I leave here.

I would think a normal breakaway switch should be able to handle the current that it has to handle in the event it is activated. This one didn't. The contacts were welded together.

How many of us have ever checked this switch? If you disconnect your trailer wiring before you disconnect the lanyard, you'll never (in the life of the trailer) activate these contacts and you'll never know if it works.

It might be a smart move to pull the lanyard, do a little pull test to see if the brakes are applied, then check for smoke at the switch to make sure this safety system is in working order. Otherwise you'll never know until it doesn't work when you need it.
 
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Old 09-04-2010, 01:57 PM   #2
HamRad
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Pbahlin,
That is an interesting experience you had. I must admit that the only time I even think about that switch is when I'm hooking up or disconnecting. Only experience I've had with that device is through another MOC member. As she was crossing some RR tracks one day the switch activated the brakes and she came to a very quick stop. Not only that but just reinserting the pin did NOT reset the brakes. We tried for a couple of hours to get the thing to work correctly. In the meantime she was blocking traffic! Thankfully just about the time the police were going to have her remove the rig from the road the thing started working. We're not sure why it started working again.

It is amazing at what such little things can bring a truck and trailer to come to a complete stop so quickly.

I'll take a look at mine before I hook up tomorrow. Thanks for reminder.
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Old 09-04-2010, 02:21 PM   #3
pbahlin
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One of the things that's nagging at me is that my 'theory' here has a lot of holes in it. I don't know when the meltdown really happened. I can only surmise that it happened the way I explained. I've thought, well maybe this thing was melting as I drove down the road. Maybe I've burned up my brakes and don't know it.

There's absolutely no evidence that my trailer brakes ever got applied. I'm certain I would have felt it on the highway if they went on and in the park I'm in, the site and roads are small stone mix and there's no way my brakes could have been on without making some serious grooves in the road. But still, I can't prove it.
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Old 09-04-2010, 04:42 PM   #4
BB_TX
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I did check mine late last year. I greased my ez-lube axles using the zerks and there has been so much discussion about getting grease thru the seals to the brakes, after a couple thousand miles I decided to see if the brakes worked on all wheels. I knew it came to an abrupt halt if I actuated the manual switch on the brake controller at slow speed. But I wanted to see each one individually. I jacked one wheel at a time just off the ground, pulled the brake away switch, and tried to turn the wheel. Each one would turn less than a quarter turn before locking up. But I pulled the breakaway switch, tested a wheel, and put the switch back in until I could raise the next wheel. Did not leave it out more than a minute each time so I guess it would not have time to heat up too much.
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Old 09-05-2010, 04:20 AM   #5
pbahlin
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Bill:

That sounds like a good annual check. I think I'll add that to my maintenance plan.

Another, quicker, check is to measure the resistance of the brake circuit at the hook up cable. Brake to ground (bottom left to bottom right pins looking into plug) should be about 1.6 ohms. A significantly lower reading would indicate a short somewhere and a significantly higher reading would indicate one brake is open circuited. That number is for four brakes. This doesn't tell you anything about the mechanics of the brake but it's a good quick wiring checkup and simple enough to do frequently.

I found mine to be 1.6 so I'm going to check this before every hookup.

Side Note: Have you noticed that the wires to your axles are pretty exposed? Mine are just hanging out in the breeze. I plan to harden these this winter; at least tie them to something to get rid of the exposed 'loop' that can catch on things.
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Old 09-05-2010, 07:22 AM   #6
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Quote:
quote:Originally posted by pbahlin

...........
Side Note: Have you noticed that the wires to your axles are pretty exposed? Mine are just hanging out in the breeze. I plan to harden these this winter; at least tie them to something to get rid of the exposed 'loop' that can catch on things.
Yes I did. One of mine was laying on the spring. So last year I bought some wire loom from Home Depot and put it around the complete length from where it exits the bottom cover to where it enters the back plate, both sides.
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Old 09-05-2010, 10:16 AM   #7
awaywego
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I check mine each time I repack wheel bearings. While one wheel is off the ground, I spin the wheel and jerk the cable. I did this last month and the wheel did not stop. I took the switch apart and corrosion had eaten the wire off the lug.
You just never know.
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Old 09-05-2010, 12:48 PM   #8
dersequim
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A few years back my Sister-in-laws Grandchild pulled the Breakaway Lanyard out and left it on the ground. We came back about 4 days later. Since we were hooked up they stayed on the whole time. The magnets melted. It was a rather expensive repair. She said she would reimburse us for it. STILL WAITING!!
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Old 09-05-2010, 02:47 PM   #9
drknapp
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I may be mistaken, but I was told the brakes still applied when disconnected from the truck by using power from the trailer's batteries? The idea being that it would help bring the trailer to a halt if it completely disconnects from the truck. Does anybody know if this is correct?
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Old 09-05-2010, 04:12 PM   #10
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Quote:
quote:Originally posted by drknapp

I may be mistaken, but I was told the brakes still applied when disconnected from the truck by using power from the trailer's batteries? The idea being that it would help bring the trailer to a halt if it completely disconnects from the truck. Does anybody know if this is correct?
That is correct. Not much of a safety if it worked any other way. Jim
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Old 09-06-2010, 03:37 PM   #11
mhs4771
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Let's ponder this: If you pull the disconnect pin, thus activating the brakes and leave the pin out while connected to shore power you will be putting max current thru little switch contacts that are normally only made for a brief period (emergency stopping of the unit upon a complete disconnect from the TV. I would be checking the Brake Magnets and other wiring to make sure that weren't damaged also. If lucky, the switch melted before damaging anything else.
I'm still in snow country of Western NY and checking the disconnect switch is part of the annual NYS Inspection of all Trailers with Electric Brakes.
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Old 09-06-2010, 03:39 PM   #12
pbahlin
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Found another way to quickly check your brake magnets.....

Apply your brake (at the controller or by temporarily pulling breakaway lanyard) while holding a compass near brake drum. If the magnet is pulling current, the compass will jerk around in response to the magnetic field. Do this for each brake to see if they're all getting current.

This is not a substitute for physical inspection of magnet for signs of wear.
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Old 09-07-2010, 05:59 PM   #13
mojavemike
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I believe that in my Prodigy book it says not to pull the emergency brake away switch with the trailer hooked to the brake controler because it may or will damage it. That is what I remember but shoiuld read my book again.
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Old 09-08-2010, 01:47 PM   #14
pbahlin
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Here's an update to my breakaway switch story...

I towed today and once hooked up did some serious braking tests with my controller. All was well. It seems my magnets didn't get fried after all. My angel must have been looking out for me. The defective breakaway switch burned up and opened the connection before there was enough time for the magnets to get damaged.

Sometimes two wrongs can make for a saved butt.
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