Factory Brake Controller Question/Issue

Update on my issue. After trying to understand how the tow vehicle knows when a trailer is or is not connected and no clear direction I was able to find, I spoke to a local trailer shop.

Was told the resistance through the brakes is how the tow vehicle detects a trailer. Anytime the resistance changes, it will throw a fit.

Guy suggested I check all connections. All connections were good, but there was a broken wire inside the drum. An ohm meter did not detect it. I was able to make it malfunction using a 12 volt source. There was also a bit of corrosion on one of the connections on the opposite of the trailer and this was causing a malfunction in the connection. Good thing to know here. An ohm meter will not catch these issues. Trailer shop said the ohm reading suggested by the manufacturer will catch most problems, but always suggests using 12 volts from a battery or battery charger. Said that is the only way we can catch those odd issues that cause the biggest problems.

To be on the safe side, I am in the process of running new brake wire from the plug to the brakes and testing everything with straight 12 volts.

Hope to finish up the wiring and take her out for a test tow tomorrow.

Will let everyone the final verdict.

Still having issues. If I set the controller with "Electric over Hydraulic", the connection issues don't rear its ugly head.

Ironically, I hooked up my flatbed trailer and not a single connect/disconnect issue.

I am at a loss.

It can't be detecting the trailer through the brake circuit as mine knows there is one plugged in even when it doesn't have brakes. The shop that told you that must be in error. Even when I plug in a small trailer that uses the 4 pin connector it knows. The first time I had a signal light burn out in my util trailer it showed up on the dash as soon as I plugged in the trailer.

Doug Morgan said:

It can't be detecting the trailer through the brake circuit as mine knows there is one plugged in even when it doesn't have brakes. The shop that told you that must be in error. Even when I plug in a small trailer that uses the 4 pin connector it knows. The first time I had a signal light burn out in my util trailer it showed up on the dash as soon as I plugged in the trailer.

Click to expand...

What year Expedition do you have?

I believe I have found an solution. I wired it up according to this suggestion found on an F-150 website.

Apparently, this issue happens to F-150's also.

I did what this guy did and sure enough, my trailer is detected. Happy guy here.

The vehicle detects a trailer is connected through the trailer braking system. Maybe the later models can detect a trailer with the 4 pin wiring, but my 2015 doesn't.

After dinner, we are hooking her up and taking her for a spin to make sure it is solved.

My F150 would detect a trailer with the 4 pin, I assumed the Ex would do the same.

Took it on a short trip (about 15 miles) around the block. Never had a connect/disconnect issue. The resistance for the controller must have needed a lower resistance.

When I checked my magnets, I was getting around 3.2 ohms per magnet. Total resistance with all 4 magnets in parallel was around 0.8 ohms. With that 6 ohm resister added in parallel, it brought the total resistance down to 0.705.

It must have been right at the edge of the Ford settings.

Now since I have the brakes working, I need to adjust them properly.

Time for a cold "adult" beverage.