yes, I know for a fact the manual override always works. I test them that way. It is much faster to troubleshoot using the manual as you immediately know if the truck wiring is good. And you do not have to move all year for the ITB to operate, only the 05s as I recall. Plus, it is not the case you get no voltage, only a couple of tenths.

If you have voltage at the seven pin on the truck and the trailer brakes work, there is a connection problem between truck and trailer.

Are you powering the trailer brakes through your seven pin cord on the trailer?

Steve

 

In my experience it is almost never the wiring to the brakes themselves and all it takes is one magnet for the ITB to find the trailer, so unless the lead is disconnected at the first brake on the streetside your ITB will find the trailer.

I realize this is driving you crazy, but normally this is a very simple system to troubleshoot and diagnose. I am betting this is going to turn to be something very simple, I worry you are overthinking it.

Steve

 

By doing this test you confirmed the the trailer brakes work but by using the on board battery that is grounded to the frame and along with the trailer brakes but you need to confirm that you have a ground from the trailer to the truck. Disconnect the on board battery ground and jump it to the white (ground) wire at the plug along with the blue wire and then see if the brakes work. I repeat you have to have a ground wire from the truck so the controller can see the brakes, grounding through the hitch does not work and you have to have a two wire circuit all the way to the brakes, the white wire can be grounded to the frame but but you need a solid ground wire to the truck.

Denny

 

I agree this sure sounds like a connection issue. The simplest way to verify the trailer brake circuit is to pull the break-away pin with the trailer unplugged. If that sets the trailer brakes, leave them alone and move on.

Put the pin back in. Do you have voltage at the truck seven pin? If so, plug back in and check connections at the metal junction box on the trailer. You have established the trailer brakes are good as far as the junction box, you have established voltage at the truck. All that is in between is the seven pin cord on the trailer and all those connections are in the junction box or should be. In this box, what are the two wires feed the brakes (the negative and positive leads) connected to?

Steve

 

Aswer to post #16 RV tech-- I'm using the 7 pin connector. New cord and new 7 pin connector.

Trailer is wired at juction box with one wire coming from the blue wire to the brakes + and ground wire routed from each brake back to the ground in the junction box with a NEW ground, burnished on the frame and back thru the trailer cord to the truck.

So to make it simple blue to trailer brakes, white to trailer brake grounds and both go back to the connector.

Will try pulling trailer brake emergency pin this evening. Headed out of town for next 3 days. Will post when I return. Trailer stays home but am pulling a large version of a ditch witch 500 miles. Will cross check truck's ITBC enroute.

 

Thank you, That is helpful. So, if I am understand you correctly, you activating the brakes with an independent power source feeding through the same plug you would use to hook your truck to your trailer and the brakes work. That should mean the trailer is good, so let's leave that out of the equation.

Now normally I would say to check your truck and the receiver on your truck, but you alreay know your truck is good as it works fine with another trailer. That also should rule out the ITB controller circuit. If, by chance the controller works manually, you have a flukey controller as you will have demonstrated a complete brake ciruit with working brakes on the trailer manually. The only thing at that point is your controller or a glitzy connection between the truck and trailer.

I wish you were here as I would like to see this one.


Steve

 

RV tech.
I will post findings after the weekend.

 

The trucks trailer harness will probably have a ground at the rear of the frame or on the receiver hitch itself. Check this too.

 

The OP said his truck works with another trailer. If true, that would argue against the problem being with the truck circuit .

Steve

 

If I'm up to speed, the trailer thats not working with this truck is a 4 brake unit, and the one that does is a 2. My thinking is that the 4 brake unit is trying to (unsuccessfully) push 12 amps back to the truck through ground. The 6 amp trailer is getting by. I dunno, it sounds like the trailer passes muster so I think the problem lies in the connection between the two. Maybe the controller is faulty. Also, to the OP, you need to measure the actual amp draw on the trailer. Just because the magnet stops a hand spun wheel doesn't mean its good.

 

If it is an amperage issue, it should be a connection issue. All the controller does is make power available up to its ability to deliver. I totally agree troubleshooting with amperage is much better, but most folks do not have equipment capable of doing so, in my experience.

Remember also his issue is a "no trailer signal" on his ITB controller monitor. It takes the resistance of only one magnet to activate that, if I recall correctly. Low amperage would be a weak brakes issue as opposed to a no brakes issue.

Steve

 

Towed a ditch witch- 5K lbs model with a 1 ton trailer and 4 brakes on trailer. 600 miles. No errors. Worked as required. New wiring going into trailer from junction box to each brake. 10 gauge. Fed up with "Trailer Fault" and "Trailer Disconnected" on the toy hauler.
Will do that this coming weekend. New 7 pin plug-6 month old cable from plug to junction box-rewiring trailer this weekend. I suspect low amperage too.

 

Following this thread with much interest--I have about the same problem with my '09 F450 and a 36' Mobile Suites fifth wheel. Some time in summer of '10, I lost the brakes in Colorado. Since then, 5 different shops have worked on the truck/trailer and I always leave with brakes. Anywhere from 30 miles to 300 miles later, the "Wiring Fault In Trailer" will come on and, no brakes. RV techs and Ford techs (Ford is almost useless, all they can do is proclaim that "the controller is working correctly"). Have replaced both the truck harness and the trailer harness. Have same problem whether using the bed plug or the factory bumper plug. Have had the in-line connector apart many times and always have power at the brake lug. Traced the harness back to first ground wire, cleaned the frame and reconnected--no improvement.
Luckily, the 450 brakes have held up, even through a trip to Alaska this last summer. Sure would like to figure it out.
Usually, I will have brakes when starting out each morning, then somewhere down the road the dash message comes on. I can usually make it happen if I have to shower down on the brakes or use them heavily for a long period.
Joe

 

I'm not sure what faults the Ford controller uses but I'm beginning to wonder if the trailer fault code is a short in the trailer wiring. I had this problem when we left to go south last fall and I had a hard time finding it. It ended up being in the wiring going through the front axle(from one side to the other), one time I had a short and the next time all was well. On my Brakesmart controller it came up as a brake short and would not allow the brakes to work until it was reset,then sometimes it would work for awhile and them fault again. I found it by cutting the axles lose one at a time. Both of my axles are now have external wiring instead of wires through the axle. I would hate to say how many times I had the wiring apart until I found it.

Denny

 

The piece of the puzzle I see missing in both of the above cases is a measure of how many amps the controller is putting out. As many of you know, I have long been less enthused about Ford's ITB controller because it pales in comparions to quality aftermarket controllers in terms of built-in diagnostics (and yes I do have an ITB in one of my trucks, so I am familiar with its operation, and no, I am not impressed).

I no longer think these are harness issues given the bountiful information preceding. What if it is simply the case the controllers are going down in high demand or repeated high demand situations? I may be wrong, but it sounds like the error messages are coming during operation, not while sitting still. In the OP's case, the controller works with a small trailer, but not a big trailer in terms of demand, possibly?

With intermittent problems, it is always the case that it takes more to diagnose the problem. What I would do in both of these cases is take my tester box with its twenty foot lead and plug it in. The I would say "let's go for a ride". I would dial up the controller to max so it was going for full output with hard stops and watch my monitor box while we went for a ride. That way I could see exactly what was happening when the truck brakes were activated and what was going on when the error messages came up. I don't know what it would show, but I sure would like to. I am going to assume here that in both cases the posters really do know what they are doing and have done all the obvious. I also am going to assume in the second case, at least one of the RV techs was reasonable in their diagnostic attempt. Doing what I am suggesting would really lay the issue of is it truck or trailer to rest because I would essentially have the trailer brakes sitting inside my monitor box in my lap.

If, and only if all was good there, would I rip the wiring out of the trailer and redo all or some of it.

When you remove what isn't, all that is left is what is. I may be a thousand miles off, but what if the reason the problems don't appear to be one of the common things is because they really aren't? One of things I have often found is sometimes techs stick too closely to established protocol. Once in a while thinking outside the box is important.

Just my two cents worth in what I find to be really challenging situations.

Steve