I've got a problem where my trailer brakes hardly engage. Summary of troubleshooting so far.

Trailer was taken in for brakes to be set, bearing repacked.
Hooked trailer to truck (08 F250 w/ Factory TBC), set gain to 10, slide slider all the way, I can hear the brakes engage, and feel slight drag, but not enough to stop me at idle. So I tell shop brakes aren't set. They hook up their truck (older chev, with prodigy controller), they hit the slider and locks brakes up. I see it myself. We decided, must be my truck.

Take truck to dealer, they replace 7pin connector at back as well as TBC module in dash. I can't get to my trailer to test, so I hook up to my brothers RV trailer, and it locks his brakes up, no problem. I figure, truck is fixed.

This weekend, I hook up to mine, and same problem as before, I can hear them engage, and feel it slightly. So I hook up my brothers truck (10 F250, Factory TBC) to my trailer, and he has the same exact problem I do.

So I think I can rule out the truck. So now, where do I start looking on the trailer. I opened up the 7pin plug, everything looks good in there, tight, clean etc. Do I just follow the cable back to the junction box underneath and hope to find a loose connection, or can someone suggest anywhere else to look?

Thanks.

 

I would suspect that some of the grease from repacking "made it" on the brakes shoes.
Pull it for few hundred feet while pulling manual brake activation and see if that will clean the stuff.

 

I would tend to think you have a ground issue myself. So I think I would start by checking all the wires.

 

The ground on the truck might be a good suggestion. I had the problem on mine, even I don't have corrosion problem.
The trailer plug grounds to the frame about 1/2 length of the bed. Even it is good size bolt, it was bad connection on mine. Had to sand the frame after removing the bolt.
But... that would not explain the problem with the brother's truck?
Ground on the trailers can be a nightmare. Most of them have very poor grounding points and rely on the hitch grounding. That can work in one position and not in another.
I do have Prodigy controller and it will self-test lot of issues. I wonder what OP has?

 

Best way to separate mechanical from electrical issues is to measure amp draw to trailer magnets. 10 plus amps, issue is mechanical with full controller activation. Less than that, one or more magnets are not doing their job for a number of possible reasons.

If I were a betting man, I would go with grounding issues given that is the #1 problem in 12 VDC related RV issues.

A good controller has enough diagnostics built in to spit the amp draw out in a heartbeat, as well as lot of other helpful diagnostics. I think that's the best reason to invest in high-end controllers.

Just my two cents worth,

Steve

 

I have the Ford Factory Brake Controller.

I was thinking trailer ground too, but I haven't started looking underneath to trace wires, thought I'd ask here incase there were some common ground points that were particularily bad.

I thought with the 7pin connector, all systems grounded thru that ground. Not the hitch. I know there is a junction box near the front under the trailer, I'll start there I suppose.

 

I have a prodigy controller kickin around from my F150, does anyone know if you can connect it to a newer super duty that already has the factory controller as well? Maybe just unhook the factory one? Is the harness still down below behind the gas pedal?

 

There was a thread on this a few weeks ago, and some of it conflicted. I say no, but another member had said yes, they will plug and play. I was told from Ford as well as Tekonsha that the TBCs will not plug and play in 2005+ trucks, the ECU will require reflashing in order to recognize the unit.
As far as the original issue, put a DVOM at the rear harness of the truck, jumper it from the ground to the signal wire, have a partner press the brake, and see what sort of current you read. If the readings are correct then the issue is with the trailer, not the truck. BTW, do you have adjustable settings on your OEM TBC? It might just be set too low.

 

I would not do that, you have already established your truck controller is working fine as you tested it with your brother's trailer. You also know neither your truck nor his truck work with your trailer, but - your trailer works with the dealership's truck. This is really an interesting problem!!

The problem has to have something to do with the interface between truck and trailer. To verify my hypothesis, do this. Hook up your trailer, but not your seven pin and pull your break-away. That should demonstrate working trailer brakes. If it does and you do not have brakes with your seven pin, it has to be a connection issue.

I would really like to hear how this turns out,

Steve

 

If I pull the break away, and they lock, when I put the pin back in does it just release the breaks? I've always been nervous of pulling the break away incase the brakes don't release.

 

Break away system applies full battery power to the brakes.
With good working brakes (and good battery) it might lock, or be close to it.
Putting the pin back will release the brakes -not to worry.
I use this way for testing the brakes, since on 6-wheels trailer just "feeling them work" is not telling much. I am lifting one wheel at the time, spin the wheel and pull the pin to see if the brake clicks in.
Don't forget to recharge the battery after.

 

Why is this strange??? Aren't all problems mysteriously fixed when the mechanic/dealership is involved? lol I honestly think that everybody on this Earth should get their ASE certifications... no car would ever break down again.

 

But, if the trailer did work with the dealership truck, it is a strange situation. I tend to be less cynical for dealerships. My experiences have generally been good.

I have seen this kind of situation in cases where the seven-pin cord from the trailer was glitzy and my hunch is that is the problem here, provided all preceding observations are correct.

Steve

 

I know, I was just joking, because no matter what it wrong with the car it seems like the problem mysteriously goes away when a mechanic takes a look at it.

 

"Murphy law"
I am home repair person. Each time when customer calls me for leaky faucet -it turns perfectly dry when I get there.