Electric Brake Controller

[red angus 2010]

Can you tell me if an electric brake controller should constantly show power at the trailer plug. I'm thinking it should show current at the trailer plug only when the truck brake petal is depressed. Thanks for the help. Please pray for me, in the span of two days I now own a livestock trailer and a gooseneck trailer. My daughters have reminded me the livestock trailer would also haul horses, this is getting worse by the minute.

 

[JMJ Farms]

I'm not 100% sure but I think you're correct. It should only show current when the brake pedal is pushed. And the current should increase with the amount of pressure applied.

 

[uplandnut]

right, it should only have power when the peddle is pushed. my guess is you have an auxiliary power wire in the wrong spot?

 

[5Cfarms]

If you're using an RV plug adapter you have to switch a couple of the wires in the adapter. Center prong and can't remember the other one

 

[saltbranch]

What trailer plug do you have? An RV 7 Pole a 6 Pole? For example my F-250 has a 7 pole and one of the poles is hot 24/7, its for an RV to charge battery/run the fridge etc.
The brake controller should only send power to the plug when brakes are being applied in my experience.

 

[Nesikep]

WRONG.. the trailer brake controller will keep 12V on the trailer brake terminal, but won't send any significant current to it, as soon as the trailer brakes are connected, it'll drop down to pretty much 0V, and the controller then knows there's a trailer hooked up..
If you can power a light or something from that terminal, there's probably something wrong, but if you are using a digital voltmeter to test, you probably will see 12V there.

One way to test.. Hook up a light.. like an old style turn signal light, or even one of those light-up screwdriver-like tester probes... it shouldn't light up, then have an assistant slowly apply the manual override for the trailer brake controller, your probe/light should gradually light up...

Or just hook the trailer up, if it rolls under normal conditions and applies brake when it should.. the wiring is right

 

[saltbranch]

I am not wrong. I am correct about the full time 12v in the plug. Nesikep you and I are on the same page as far as how the brake controller sends power to the plug.
When the brakes are not being applied you should not see much if any voltage to the plug terminal, I would expect to see zero or no light lit up on my tester. As the brakes are applied the voltage is sent to the plug terminal to engage brakes on trailer.
THis is an industry standard wiring diagram. Now on my trucks/ trailers I change it to my own diagram. I put my trailer brakes where the the 12v from the battery is. My intentions are if anyone steals my trailer, hooks up the plug the trailer brakes are engaged at hook up. They would have to leave the plug unhooked to take trailer and again I hope the cops might pull them over. I have a crossover plug wired up for when I let someone use my trailer. This does work as a my Dad figured out when hooking up his new truck to my trailer at our property.

 

[Nesikep]

I'm saying it depends on what you're testing with.. a high-impedance tester that puts virtually no load on what you're testing will read significantly above 0V, possibly 12V.. something which draw some power (such as a lamp) will not light up though

Interesting idea on the crossover plug!

 

[Ol' 243]

Nesikep is RIGHT, always some voltage on trailer brake controller output.