Breakaway switch testing

[C&G in FL]

Originally Posted by rubicon327

Carl: Always thought the brakes hummed too but wonder if there are variables like temperature that matter. A few days ago I pulled the breakaway pin to test after doing some rewiring in the trailer and heard nothing at the wheels. Proceeded to jack up each wheel and they were locked. No humming.

Dave......could be weather related I suppose. I always get a hum but it is generally warm when I have tested them, either by pulling the breakaway cable or by having my spouse apply the brakes manually from the driver’s seat of the tow vehicle.

[Raspy]

Dave, That makes a lot of sense. I didn't think about the seven pin still being connected.

[Raz]

Originally Posted by CPW

Dave......could be weather related I suppose. I always get a hum but it is generally warm when I have tested them, either by pulling the breakaway cable or by having my spouse apply the brakes manually from the driver’s seat of the tow vehicle.

I too have heard the hum but why do they hum as they are being energized by DC?

[C&G in FL]

Originally Posted by Raz

I too have heard the hum but why do they hum as they are being energized by DC?

Beats me. It has always been my experience that I can hear them if I am close to them and there is no loud background noise. And I’m not trying to be contrary, but I have no reason to determine why they hum. This question might be better answered by an electrical engineer.

[Raz]

I am an EE and I have no idea. I think we need a physicist. Vibrating domains and such.

[Terry G]

Originally Posted by Raz

I am an EE and I have no idea. I think we need a physicist. Vibrating domains and such.

Or maybe an exorcist?

[Raspy]

If the brake controllers use PWM to modulate the delivered power to the magnets, it would explain the hum. And I don't see why that power would need to be smoothed out with a capacitor. It seems that is how they work, otherwise there would be a big heat producing resister in the controller.

One possible proof would be if they hum when energized from the brake controller, on a setting less than full on, or 10, but not from the breakaway switch.

I have ceiling fan with a DC motor that hums too.

[Raz]

Folks said they get the hum when they pull the break away switch which is why I asked the question. I have heard the hum but I don't recall if it was during a test of the breakaway switch. I agree, the controller no doubt has a PWM circuit. It's the best way to control DC. Unfortunately, my trailer is getting buried in snow and the battery is in the basement, so someone else will have to do the testing.

[ldsharp]

I think the wise choice is to test with the 7pin disconnected... A good time to test is during/after bearing service and/or brake adjustment, both when the wheel is off the ground, free to rotate, and easy to observe. Its also a good way to judge the effectiveness of the brakes after adjustment by trying to rotate the wheel.



If my trailer "breaks away" free of the hitch and chains I could care less if 12 volts (or surge pulse) fries my controller as long as the Casita stops without destroying someone's life (and a far second case the insured Casita).

[Raspy]

Originally Posted by ldsharp

If my trailer "breaks away" free of the hitch and chains I could care less if 12 volts (or surge pulse) fries my controller as long as the Casita stops without destroying someone's life (and a far second case the insured Casita).

If it breaks away from the hitch and chains, it will also disconnect the seven pin.

Rubicon said it the best. It seems like a good idea to have the seven pin pigtail and the breakaway leash longer than the safety chains. And the leash longer than the seven pin pigtail. That would allow a controlled stop, possibly without any damage, in the even the trailer was hanging on the chains.

[Mike_L]

Having the tongue of the trailer separate from the ball of the hitch is something you never want to happen, especially if you are moving. Likewise, having the breakaway switch activate while moving isn't good either. On my way home from the Dealership with my last new trialor the breakaway switch activated because they didn't adjust it properly when they hooked it up. The trailer wheels locked up and it stopped the trailer and tug quickly. I got a lot of "hand signals" from other drivers but no collisions! I did see the results of another trailer separating from the hitch. The safety chains kept the trailer tongue from hitting the pavement. The breakaway switch activated and the trailer brakes locked up. It appears the trailer dragging back against the tug kept the safety chains tight and helped to keep the trailer tongue supported. Should the trailer completely separate from the tug, the breakaway switch would lock the trailer wheels to stop it more quickly.

[rubicon327]

Originally Posted by Mike_L

Likewise, having the breakaway switch activate while moving isn't good either. On my way home from the Dealership with my last new trialor the breakaway switch activated because they didn't adjust it properly when they hooked it up. The trailer wheels locked up and it stopped the trailer and tug quickly. I got a lot of "hand signals" from other drivers but no collisions!

This is particularly problematic for other drivers behind you because the brake lights do not light up upon activation of the breakaway switch.

[WaltP]

True, but it would be even worse for them if there were no emergency brake.
Walt

[rubicon327]

Originally Posted by WaltP

True, but it would be even worse for them if there were no emergency brake.
Walt

Of course under a true breakaway condition. I was responding to Mike_L’s specific situation of the breakaway system activating while he was still hitched.

[Raspy]

Originally Posted by rubicon327

This is particularly problematic for other drivers behind you because the brake lights do not light up upon activation of the breakaway switch.

They do on a Black Series trailer, unless it has been altered.

Black Series uses a Curt breakaway controller that gets activated by the breakaway switch. It has the emergency battery, a charger for that battery, wiring to the brake circuit and an output for brake lights that feeds through diodes into the brake light circuit.

Brake lights working with the breakaway system might even be an RVIA requirement for certification, but I'm not sure about that.

Most or all modern trucks, set up for towing, have a trailer brake test system that alerts you if the trailer becomes unplugged. This is done by voltage pulses put into the trailer braking circuit that the truck can read. It knows if there is an open circuit and alerts you on the dash. One of the problems with this system is that is can feed into the breakaway control box and feed through the diodes into to brake light circuit. When this happens, the brake lights blink at about once per second in response to the test pulses, almost like the emergency flasher system.

On mine, I decided the dedicated emergency battery and control box was a bad idea and removed it. Now, the breakaway is powered by the house batteries. And in the process, I fixed the blinking tail lights.

The house batteries are a better source for breakaway braking power because you always know they are charged when you are using the trailer, but with the emergency battery, there is no way to always know if it is charged, unless you keep testing it frequently.

[Tug Hercules]

When the Breakaway Switch activates, either in an Emergency or in Testing, how do You deactivate it?

i.e. once the Trailer Brakes lock up, how deactivate ??

Thank You.

[Radar1]

Originally Posted by Tug Hercules

When the Breakaway Switch activates, either in an Emergency or in Testing, how do You deactivate it?

i.e. once the Trailer Brakes lock up, how deactivate ??

Thank You.

They are activated when the plastic pin is pulled out of the breakaway switch aloowing the electric circuit to complete. To deactivate them, simply plug the plastic pin back into the switch to break the electric circuit.

[Joe MacDonald]

Once you are safely stopped, and are getting ready to re hitch, plug in the pin that pulled out to activate them, its re-useable, and self explanatory once you look closer

Joe

[THene1713]

Originally Posted by AC0GV

When tripping a breakaway switch while connected, and the voltage back feeds the tow vehicle, will it damage the controller or on-board computer? Mine is factory installed on a Ford F150. But I recall warnings years ago in another RV group, that it would damage things.

If properly wired, the break-away should simply apply 100% of TOAD/TRAILER battery voltage to the trailer brakes/ toad brake operator.

[Mike_L]

Trailer brakes are electric. An electromagnet is activated when it receives power to apply the brakes. The plastic plug in the breakaway switch keeps two internal electrical contacts from connecting to keep the circuit open which prevents the magnets from activating. Removing the plastic plug allows these electrical contacts to come into contact with each other, close the circuit and activate the magnets to apply the brakes. Reinserting the plastic plug separates the internal electrical contacts to deactivate the magnets and release the brakes.