Yesterday, I replaced the cable that connects the 5th wheel to the 7 pin connector on the truck. Luckily, the cable I ordered used the same color scheme as the existing cable (I tested old and new cable with a multimeter) and after connecting everything, the tail lights, turn signals, brake lights and running lights all worked as they should.Then I decided to test the breakaway switch. I could not tell that anything happened when I pulled the pin. I checked the wire from the breakaway switch and I had voltage. Today, I tested it again after filing the contacts in the breakaway switch with a nail file. Again I had voltage (I think it was 12.5V), but the brake lights don't come on and I don't hear the brakes humming. I reattached the cable to the tow vehicle, and I can hear the brakes humming when the brake pedal is pressed as well as when the manual switch is pressed on the brake controller.Shouldn't the tail lights come on when the breakaway switch is tested? I suspect that not enough current is passing through the breakaway switch to activate the brakes and the brake lights (I don't have an ammeter to test it.) I have already ordered a new one from Amazon.

I don't think the brake lights would work with thru the break away switch. First the switch is not connected to the light wiring harness. That wire goes straight to the brakes. So the lights will not know when the brakes are activated. And I have been behind a 5er when the breakaway switch was pulled, and no brakes light was seen. Also remember the brake away switch is activated thru the trailer battery.And NEVER pull the break away switch with the 7 pin plugged in. You "can" destroy your brae controller.

The wheel brakes and brake lights are separate circuits. Actually the brakes lights are divided into left and right side... The breakaway switch will not activate any lights, only supply the brake magnets with the trailer battery voltage.

bearwayne wrote:Yesterday, I replaced the cable that connects the 5th wheel to the 7 pin connector on the truck. Luckily, the cable I ordered used the same color scheme as the existing cable (I tested old and new cable with a multimeter) and after connecting everything, the tail lights, turn signals, brake lights and running lights all worked as they should.Then I decided to test the breakaway switch. I could not tell that anything happened when I pulled the pin. I checked the wire from the breakaway switch and I had voltage. Today, I tested it again after filing the contacts in the breakaway switch with a nail file. Again I had voltage (I think it was 12.5V), but the brake lights don't come on and I don't hear the brakes humming. I reattached the cable to the tow vehicle, and I can hear the brakes humming when the brake pedal is pressed as well as when the manual switch is pressed on the brake controller.Shouldn't the tail lights come on when the breakaway switch is tested? I suspect that not enough current is passing through the breakaway switch to activate the brakes and the brake lights (I don't have an ammeter to test it.) I have already ordered a new one from Amazon.No, the brake lights are not wired to the breakaway switch..No you will not hear any "humming" at the brakes, the break away switch sends pure 12V DC to the magnets.. There is no way pure DC will "hum" in any way shape or form..You can check to make sure your brakes are working when the break away switch is activated by using a compass, by jacking up the wheels and trying to turn them by hand.. or my favorite way, use your vehicle (with the trailer to vehicle cable disconnected) and see if the brakes slide the tires..

I was testing my brake drum drag and noticed sometimes when I engaged the electric brakes nothing happened until I turned the wheel about a quarter turn...Must be some kind of mechanical thing has to happen first ???Also on my fifth wheel I hear the tone when the electric brakes are engaged but on my POPUP trailer I don't hear a tone...I know the brakes were engaged as I was using a compass I carry in my glove box and the needle was changing when the brakes were engaged...Roy Ken

At the bottom of this page is an electric brake animation, you can see the magnet needs to move (the wheel needs to turn) for the brakes to activatehttp://www.axleinc.com/electricbrakesdrums.html

Breakaway switch and brake lights | Good Sam Community

15 Replies

red31
Explorer
Nov 16, 2015
At the bottom of this page is an electric brake animation, you can see the magnet needs to move (the wheel needs to turn) for the brakes to activate

http://www.axleinc.com/electricbrakesdrums.html
RoyB
Explorer II
Nov 16, 2015
I was testing my brake drum drag and noticed sometimes when I engaged the electric brakes nothing happened until I turned the wheel about a quarter turn...

Must be some kind of mechanical thing has to happen first ???

Also on my fifth wheel I hear the tone when the electric brakes are engaged but on my POPUP trailer I don't hear a tone...

I know the brakes were engaged as I was using a compass I carry in my glove box and the needle was changing when the brakes were engaged...

Roy Ken
Gdetrailer
Explorer III
Nov 16, 2015
bearwayne wrote:
Yesterday, I replaced the cable that connects the 5th wheel to the 7 pin connector on the truck. Luckily, the cable I ordered used the same color scheme as the existing cable (I tested old and new cable with a multimeter) and after connecting everything, the tail lights, turn signals, brake lights and running lights all worked as they should.

Then I decided to test the breakaway switch. I could not tell that anything happened when I pulled the pin. I checked the wire from the breakaway switch and I had voltage. Today, I tested it again after filing the contacts in the breakaway switch with a nail file. Again I had voltage (I think it was 12.5V), but the brake lights don't come on and I don't hear the brakes humming. I reattached the cable to the tow vehicle, and I can hear the brakes humming when the brake pedal is pressed as well as when the manual switch is pressed on the brake controller.

Shouldn't the tail lights come on when the breakaway switch is tested? I suspect that not enough current is passing through the breakaway switch to activate the brakes and the brake lights (I don't have an ammeter to test it.) I have already ordered a new one from Amazon.

No, the brake lights are not wired to the breakaway switch..

No you will not hear any "humming" at the brakes, the break away switch sends pure 12V DC to the magnets.. There is no way pure DC will "hum" in any way shape or form..

You can check to make sure your brakes are working when the break away switch is activated by using a compass, by jacking up the wheels and trying to turn them by hand.. or my favorite way, use your vehicle (with the trailer to vehicle cable disconnected) and see if the brakes slide the tires..
boogie_4wheel
Explorer
Nov 16, 2015
The wheel brakes and brake lights are separate circuits. Actually the brakes lights are divided into left and right side...
The breakaway switch will not activate any lights, only supply the brake magnets with the trailer battery voltage.
Terryallan
Explorer II
Nov 16, 2015
I don't think the brake lights would work with thru the break away switch. First the switch is not connected to the light wiring harness. That wire goes straight to the brakes. So the lights will not know when the brakes are activated. And I have been behind a 5er when the breakaway switch was pulled, and no brakes light was seen.

Also remember the brake away switch is activated thru the trailer battery.

And NEVER pull the break away switch with the 7 pin plugged in. You "can" destroy your brae controller.

Forum Discussion

Breakaway switch and brake lights

15 Replies

About Technical Issues

Related Content

Breakaway Switch Confusion.

Autimatic Transfer Switch?

Breakaway Switch

Breakaway Switch

WIFI Light Switch