Hi! I have recently bought a 2015 XLT with an OEM Ford trailer package. I also recently bought a double axel trailer (GVWR 8300lbs). I do not feel I am getting adequate braking performance from the trailer. The controller recognises when the trailer is connected. At level 10 on the OEM gain controller I can feel the trailer brakes kick in, however at no speed will the brakes lock up on dry pavement.

My real concern is when I apply the foot peddle. Are my trailer brakes working or is the truck doing all the work? I can't tell. Ok, so I put a multi-metre on the 7 pin plug and had my wife pump the brakes whilst standing still. I only got 3.5 volts out. A tech I know told me that the controller will not put any voltage out when the truck is standing still. He claimed that the controller only puts out 12 volts at speed. ie proportional to speed. True? I don't know. I can hear the magnets are working. I have adjusted the self adjusting brakes. So, bottom line, is my tech friend correct and the brakes are working correctly, or are is the controller bad?
Many thanks !

 

He is correct, if you go into the trailer menu, you will see that the ITBC only gives you a few bars when at a stop. This is normal, it reduces braking effort when you drop below 20mph to prevent locking up the trailer tires when you don't have time to back off (like when slowing for stopped traffic).

At 25mph or above, the ITBC should be able to lock up the brakes. However, before you go digging into the truck, check that your trailer brakes are properly adjusted. They often aren't, even when brand new. Once you know the trailer brakes are squared away (should also do a resistance test between the magnet to + and magnet to -, and also ohm out the magnets), and have cleaned the 7-pin at the truck and trailer, and unplugged both connectors underneath the bumper to clean and grease, and have ensured the ground strap under the rear bumper is tight, THEN if you still can't lock up the trailer brakes, investigate further.

 

Many thanks for that - dumb question: what is meant by ITBC?

 

Integrated Trailer Brake Controller

 

Many thanks for that, it gives me confidence that my brakes might be working correctly. However, I don't know what is meant by: "should also do a resistance test between the magnet to + and magnet to -, and also ohm out the magnets". Could you give me a little more instruction? Thanks.

 

Check out the video below. One of the best I've come across on how to properly set up your trailer brakes. Find a nice gravel area to do braking testing on is key.

 

Main thing to know about the brake operation is the voltage has to change from zero to system 12 volts >smoothly<<.
The trailer brakes are magnetically operated.
The higher the voltage applied, the more current flows, the more the electro -magnets apply braking force.
You have to set the force applied by testing since every trailer is not the same weight, same number of wheels etc.
Put this all together and it's just common sense.

 

Through the wiring in the magnet you should have resistance, it varies by mfg, but about 4Ω for 7 inch brakes, with larger brakes having less resistance. Checking this tells you if you've got a failing magnet.

The other two are checking resistance in the brake wiring, from the magnet to the 7-pin. Both should be very close to 0Ω. Having resistance in the wiring (corroded connection points, pins) reduces the voltage at the magnet, reducing it's braking power.

 

I second it being a trailer issue. I had exactly this problem when I put an axle and new brakes into my utility trailer. I knew I had them adjusted correctly, so couldn't figure out what was going on.

I read that new trailer brakes need to be driven for a while to wear in. I didn't believe I would see that kind of difference, but after 150 or so towing miles I can now lock up the brakes at gain 6 without me doing anything to the truck or trailer.

 

No one asked if they are disk or drum brakes. If you have not checked, may want to go back to the brake controller and check for that option never know how the original owner was using it. The reason I suggest this is I was speaking to a Dexter Company brake specialist and he spoke about that option as we were discussing up grading to disk brakes. I have drum brakes on my trailer. I can easily lock up my brakes if I increase the braking setting as the trailer is slowing to a stop. See edits at the bottom ** Now the way I was taught, is you increase the gain until the wheels just start to lock up as the trailer is coming to it resting stop. From memory mine are running at a setting of 4 or 5 right now. There has been several good suggestions, I too would suspect the trailer as more likely or starting at the trucks connection in the 7 pin connector and moving back. Just a guess.

After my trailer has set for a month or probably longer I usually notice its braking takes a few stops before becoming fully elective as it was the last time I was out. My brakes are manual adjusting. As the brake shoes ware, the brakes become less effective due to the fact that the magnet has to move farther to make up for the ware in the brake shoes. The magnets are pulling against a spring, the further it need to move the more current required to over come the spring's increasing tension. That being said if a persons brake shoes are several clicks out of adjustment, they wont have much braking or even with the brake controller at maximum voltage. I usually adjust my trailer brake shoe about 2 or 3 click back from fully tight shoes as when tightened from center them the drum. At the released setting there is almost no drag or just an occasional touch of drag. Too tight is not good either. I like to use a ohm meter to check for grounded magnet coils, one grounded coil will stop your brakes from working. If there are no grounded magnets, then applying 12 volts to each of the magnets and checking their current draw is my final test. Shorted coil winding are hard to measure with a ohm meter because each shorted turn of wire does not make a significantly difference in the ohms reading but shorts can bypass many turn of wire in the coil reducing its effectiveness. There are a lot more details to explain, this is just a high light of where I might start.

Edit ** Flamingtaco graciously in his post #13 says NO politely to my lined out brake testing part and has a good reason, Ford has a different trailer brake setup/testing procedure.
Thanks for bringing it to our attention.

This is quoted from the Ford 2018 F150 Owners Manual V5 page 308 "5. In a traffic-free environment, tow the trailer on a dry, level surface at a speed of 20–25 mph (30–40 km/h) and squeeze the manual control lever completely. 6. If the trailer wheels lock up, indicated by squealing tires, reduce the gain setting. If the trailer wheels turn freely, increase the gain setting. Repeat Steps 5 and 6 until the gain setting is at a point just below trailer wheel lock-up. If towing a heavier trailer, trailer wheel lock-up may not be attainable even with the maximum gain setting of 10."

Constructive thoughts are always good, Thanks Flamingtaco
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