Breakaway Switch Question

[stg2500]

How can you tell if the breakaway switch is functional on a trailer? I have pulled the cable out and checked for voltage at the brakes. There is voltage present but the brake lights are not on. Is this correct?

 

[Thomas]

Brake lights/turn indicators have a separate source of +12 volts on the typical 7 pin plug. Applying power to the brakes has nothing to do with the stop lights.

 

[wcjp]

You could pull the pin on a dirtroad. Try towing for 5ft. Did the tires lockup?

 

[B.G. Smith]

Breakaway

Very good idea to check the switch if you want the brakes to work in case of disconnect from tow vehicle. I had one on a travel trailer where the strips where the contacts are mounted had warped and when the pin was pulled the contacts were still apart. If you have voltage to brakes with pin out I would say they are working, this puts full voltage to the brakes and they react accordingly, I accidently pulled the pin coming out of a parking space in Mississippi and I thought I had hit a concrete wall. bg

 

[Motorhead]

F. Y. I. The break-away system only works off of the aux. battery in the trailer. Dead or no battery in the trailer = no break-away braking. Chris

 

[stg2500]

Originally posted by Motorhead

F. Y. I. The break-away system only works off of the aux. battery in the trailer. Dead or no battery in the trailer = no break-away braking. Chris

That is why I added the charger to the trailer since it did not come with it!!

 

[Davison]

breakaway switch

FYI: I've read numerous times in trailer manuals that we are supposed to 'test' the breakaway switch monthly by pulling out the plastic plug and verifiying that it is working. I've verified like the previous post - pull on the trailer and if it resists, it is working.



Confession. I've never been conscientous about that. In almost 20 years of towing a travel trailer, I've maybe done the test less than a dozen times.



I hope to change my baaaad habits.

 

[Deezul1]

Another easy way to check is to pull the pin and hold a magnetic compass by the wheel, the needle will turn towards the wheel.

 

[RustyJC]

A word of warning. If you're planning on testing the breakaway switch by pulling the pin with the trailer hitched to the truck, be aware that many (if not most) brake controller manufacturers warn against pulling the breakaway pin with the truck-to-trailer umbilical connected. The back EMF from the trailer battery present on the truck's blue brake wire when the breakaway pin is pulled can fry some controllers.



Unplug the umbilical before you test the breakaway switch.



Rusty

 

[Davison]

Rusty: Good point about the umbilical cord!! Makes sense. I'm gonna do that. Thanks!