Testing Breakaway Brakes Dos and Don'ts

[Bruce H]

You should not test your trailer's breakaway brakes by pulling the pin while your trailer is plugged into your tow vehicle. The voltage from your trailer battery can back feed through the wiring and damage your computerized brake controller. When you test your breakaway brakes (and everyone should) unplug your trailer from your tow vehicle first THEN pull the pin from the breakaway switch (that is attached to the cable that should be separately fastened to your tow vehicle to physically pull the pin out, activating the trailer brakes, if the trailer comes loose). Then try pulling the trailer slowly for a few feet and see if you can tell if its brakes are working. After testing reinsert the pin before you plug your trailer back in to the tow vehicle. If you don't replace the pin the trailer's brakes will remain applied and it will quickly drain the trailer battery, even if the trailer is not hooked to a tow vehicle. You may have to turn the pin 90 degrees to get it to plug in correctly.

[Bruce H]

Regarding brake controllers; I found this interesting wickipedia article about Ford integrated brake controllers:

https://en.wikipedia.org/wiki/Ford_TowCommand

What I found interesting is that the Ford controller is wired into the vehicle's computer system and when it senses that the tow vehicle's anti-lock brake mode is activated, it instantly reduces voltage to the trailer which gives some limited anti-lock brake function to the trailer's electric brakes. Even though electric trailer brakes are not designed to be anti-lock brakes.

[Bonnie RB]

This is an older post, I realize, but we've just acquired a new-to-us Casita 17 and this is our first trailer with electric brakes. I've towed with hydraulic 'surge' brakes on several different trailers.

Should the unthinkable happen and the breakaway pin gets pulled while the 7 pin connector is attached, what happens to the under dash brake controller?
It a near certainty the controller is smoked, or is the risk of internal electrical damage reasonably low?

Do I just get in the habit of leaving the 7 pin plug and socket the last to connect, the first to disconnect, just so that clumsy me doesn't snag the cable and pull the pin when taking a 'shortcut' over the tongue when hitching / unhitching?

Jon MB, the other half of Bonnie RB.

[Travelin2]

I think you are worrying about nothing. If the day ever comes when that pin gets pulled while you are towing, having that little controller get fried is the least of your worries.

When you pull that pin it merely connects 12 volts to the brake system that normally has 12 volts hooked to it. The sky is not falling. Don't worry about the controller. The designers know we are all a bunch of bumpkins and have designed the controllers to protect us from ourselves.

[Casita Greg]

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[WizWid]

Originally Posted by Casita Greg

And if you do pull the break-away cord out to perform the unnecessary "test", be sure to immediately plug it back in again, (which can also be a bit of a challenge to do once it has been pulled out,) because if you leave it removed, you are not only depleting your trailer's battery, (the least of your worries,) but worse yet, is you will fry the brake magnets inside the wheel drums. Then you are looking at rebuilding both wheels and replacing all the wheel's "innards" because you burnt everything up.

That doesnt seem right. They are just electromagnets that consume at most 3A each.
Why would they "burn up" if left on indefinitely?

[Casita Greg]

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[WizWid]

Originally Posted by Casita Greg

Keeping them energized continuously will overheat the brake magnets. They are only designed for intermittent application, as in normal braking sequences. If you apply power to them for extended periods of time, you will destroy them.

Then why do we hear so many stories of pin accidentally pulled - followed by flat battery, followed by everything works fine after putting the pin back and recharging?

[Borrego Dave]

Originally Posted by widgetwizard

Then why do we hear so many stories of pin accidentally pulled - followed by flat battery, followed by everything works fine after putting the pin back and recharging?

Most likely the trailer wasn't moved before the battery went dead.

[gordon2]

Originally Posted by Bonnie RB

..

Should the unthinkable happen and the breakaway pin gets pulled while the 7 pin connector is attached, what happens to the under dash brake controller?
It a near certainty the controller is smoked, or is the risk of internal electrical damage reasonably low?....

You did not mention the make and model of the brake controller so this might not apply to you.

You got me thinking, and part of my thinking was that I knew the answer to your question, at least as it relates to my Tekonsha P-3, but I wanted to double check. So I asked specifically about the P-2 and P-3, and could they be damaged when the break-away switch is activated. This is the reply:

Thank you for contacting Tech Support. If the breakaway battery is wired correctly, negative to ground, and positive to the brake wire, there will be no damage to the control, if the breakaway pin is pulled. Pulling the pin (with a correctly wired battery), and activating the control, will cause no harm to the control, either. If the breakaway battery is wired backwards, positive to ground, and negative to the brake wire, it may destroy the control. If I can be anymore help, please let me know.

Best Regards,

Danny Dunn
Technical Service
Horizon Global
(888) 785-5832

[Bonnie RB]

Gordon, Thanks for that worry reduction.


Jon MB (Bonnie's other half).