Ford Super Duty 6.7 brake controller TBC - learned something new

porthole

Retired
One of the key reasons for choosing The Ford over GM and Ram 5 years ago was some of the advanced features, mainly the trailer brake controller.
Ford uses a hydraulic sending unit in the brake system to give feedback for the TBC instead of the typical brake light circuit and inertia inputs. IMO this allows better control over trailer braking.
Other benefits are a hill hold feature, trailer anti sway, limited anti lock and a lane change blinker form 3 blinks to 5 blinks.

Note on anti lock, there is a contradiction in the manual.
Page 257
  • Avoid towing in adverse weather conditions. The TBC does not provide anti-lock control of the trailer wheels. Trailer wheels can lockup on slippery surfaces, resulting in reduced stability of trailer and tow vehicle.

Page 258

  • The TBC interacts with the brake system of the vehicle, including ABS, in order to reduce the likelihood of trailer wheel lock-up; therefore, if these systems are not functioning properly, the TBC may not function at full performance.

Part of the programming is a reduced output to your trailer brakes under 11 mph speed. This is to limit the "tugging" you may get in stop and go traffic.

Page 258

  • The TBC is equipped with a feature which reduces output at vehicles peeds below 11 mph (18 km/h) so trailer and vehicle braking is not jerky or harsh. This feature is only available when applying the brakes using the vehicle’s brake pedal, not the TBC.

So, I had a goal to have the dash monitor to "know" when my boat trailer was hooked up for 2 reasons, one so that the monitor would track trailer mileage, but mainly to have the 5 blink lane change feature. I made up this bulb and socket thing. It is wired into the 7 way's connector on the brake circuit. It will sit inside the trailer tube. With the resistance of the bulb the TBC now sees a "trailer" connected. Goal accomplished, TBC shows my Whaler 21 and the turn signal blinks 5 times.

What I found out was a bit on the TBC control. I did not measure voltage, just used a visual of the bulb. Activating the TBC's manual lever from off to max had the bulb glowing as you would expect, from off to very dim to full brightness. Stepping on the brake pedal was a different result. Just enough pressure to turn on the brake lights yielded no TBC output. More pressure, more light. Applying full pressure to the pedal and the bulb seemed to be only about 1/4 to 1/3 of full brightness. But, after 5-6 seconds the bulb came on full bright.

So an in the driveway only test; it would appear applying the truck brakes just enough to light the brake lights will not activate the trailer brakes at all, or in my case get the pump spinning to build up some pressure. This would explain why the Ford drivers may experience more off a felt delay with electric over hydraulic trailer disc brakes.

When I find another spare 7 way I will do the test a little different. I'll hook up another bulb with a voltmeter and go for a ride to see how it reacts. I should be able to do this with and without a trailer since my truck has two 7 way receptacles.
 

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Gary521

Well-known member
Don't want to get into a Ford, GM and Ram debate but you are incorrect as to how the other brake controllers work.
 

porthole

Retired
Don't want to get into a Ford, GM and Ram debate but you are incorrect as to how the other brake controllers work.

Then why don't you post the correct way?

I don't really remember how the Ram and GM work, don't really care since my decision was 5 years ago. But if you post the correction to my error I'll adjust my thread accordingly.

- - - Updated - - -

And this is not a Ford vs Ram vs GM debate, so don't make it one.

The Super Duty has a hydraulic transducer in the brake system, and the way it works was a deciding factor I used, not which is better. I've owned all three, they all have plusses and minuses.
 
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