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Brake controller

D

Dan T in MO

Member
I bought a trailer to haul my tractor yesterday. Hooked up to it to pull it home and had no tail or brake lights. But to top it off, the wheels on the front axle wouldn't turn. I disconnected the pigtail and drove it home.

I got to checking wiring on the truck and trailer. Looks like the lights just need new wires and lights. The black (battery?) wire on the trailer is just a dead short. But it's not used anyway. But the blue (brakes) wire is hot from the truck all the time. An online source says my controller is fried. Hoping someone has some good news for me.
 
If you have a round pin to flat pin adapter used, check the wiring. There are two ways they are wired, some can be taken apart and switch the brake wire and 12 volt feed wire.
 
Is it a 6 pin round connector? Check the wiring configuration on the trailer. Some have the center pin as the brake controller, and some have the center pin as 12 v hot to the trailer for aux lighting and or to charge the trailer battery.
 
Is there an auxiliary brake battery on the trailer? If there is check to make sure the break-away plug is functioning. I had a similar problem with a new 7x12 enclosed trailer I bought. Plugged it in and brakes were locked on. the break-away plug was bad and I had to disconnect the battery charge wire to get home.
 
How are you testing, volt meter or test light? Try testing the brake wire from the truck with a test light. If it's passing enough to light the test light, something is wrong with the controller or it's wired wrong.

The wiring on the trailer is anybody's guess. Go through it wire by wire and see what's there. If it has those little blue fold over wire connectors... Get rid of 'em! Worthless!!!
 
I was using a volt meter. I'll try it again with a test light. Going through the wires on the trailer, I've come to the conclusion that the only wire hooked up correctly is the blue wire. So, I'm crawling under it in the next few days and putting it right.

The truck has a 7-blade RV and the trailer was 6-pin. Since it needs re-wiring, I'm going to go with 7-blade. I got a new 7-blade pig tail from Orcheln's and confirmed with the volt meter which wire was which. To check the trailer, I used a 12 volt battery and hooked each wire individually to see what lit up. I have a left brake light, but that's it. And it was the wrong color insulation.

There is no battery on the trailer and no break-away system. I might go ahead and add that while I'm at it.
 
Just a note of caution, I bought a new trailer pigtail when I redid the lights and brakes on my trailer. Much to my chagrin, the wire color code on the pigtail did not match the normal trailer color code. When I asked the dealer, they said we know, here is the color code for the pigtail.

Rich
 
You know those 7-to-6-way adapters are set up so you can switch which pins the constant power and the trailer brake power go to, right?

It"s funny when you take 3 minutes to switch it and the trailer brakes work right after the boss just told you the brake controller is the reason the brakes lock up on that particular truck/trailer combo.
 
T, I'm not sure you heard me. I took a 7-blade pigtail and put it in my plug. Then I checked each wire coming from the pigtail. I turned on the left blinker and checked the wire color coded for left blinker. Yep, 12, 0, 12, 0, etc. Then the right blinker, then tail lights. Everything gave the correct voltage for the correct color code EXCEPT the blue wire read 12 volts with nothing on the brake pedal.

Ed, it's a 02 Ford. I haven't pulled anything with electric brakes since 2007, so maybe the controller went bad from non-use.
 

I have a power indicator that plugs into the socket on the truck. It has about four lights that tell you what has power and what doesn't. Always helpful to know which side of the plug the problem is. Another help is a socket that you can hook your battery charger onto to trouble shoot trailer without the need for a vehicle.
 
I'd guess you've got other troubles. Why would your controller go bad without a load on it?

You said you plugged the trailer into the truck, which means you had to use an adapter, which is why I mentioned that they can be switched.

Supposedly brake controllers supply 12 volts pulsed, but your DVM can show steady voltage. And what they do is pulse it faster to apply the brakes.

That's how it was explained to me. I don't build them so I can't say for sure.
 
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