Brake Controller Output

[gdmercad]

I am pulling a 14.5K 5th wheel trailer with my 2013 Ram 3500 dually. During the process of setting the trailer electric brake controller, I had to put 10% gain before I had the ability to slow the unit down from 20 mph with the manual slider on the controller. I had the controller set at Heavy Electric.

I conducted a test, which I am not sure if it was the correct way to check the output from the controller.

With the trailer cable hooked up to the 7 pin connection in the bed, truck running, I took a voltage reading with a Flukes Multimeter at the brake pin located at the 7 pin connector on the bumper and got the following:

Controller set at 5% gain- 50% brake-1.9 vdc, 100% brake-6.38 vdc.
At 10% gain- 50% brake-6.3 vdc, 100% brake-7.46 vdc.

In addition to the above voltage checks, I also checked amps with a clamp amp meter at each wheel magnet with the following results:

Controller set at 10% gain- amperage at each wheel was- 1.75, 1.78, 1.77, 1.76. Dexter manual specifies 3 amps

Is this the correct way to check controller output? If so, are the output voltages in the ballpark? Does the speed of the truck affect output from the controller when braking is applied? Any assistance would be appreciated.

 

[grabinov]

I've always set mine by the old school "brake check" method. Give yourself some room in a parking lot where you can roll with the trailer attached. Increase the gain until the point where a quick "press" of the controller lever all the way will "lock" or "chirp" the tires on the trailer. It helps to have someone watching as you often can't tell, since some of the tires will lock and others will not - trailer brakes not being of the highest or most consistent quality and weight distribution not being perfect. This often takes more gain that you would expect, but it will get you close to the point where a full push of the pedal will get you a full 12 volts.

Thinking out loud:

I am not sure about the system in the new trucks (though I have the same 2014 truck) but many aftermarket controllers won't give you full voltage unless you have not only a hard press of the brakes, but a hard press of the brakes that leads to a change in momentum (hard braking not just hard brakes). That is because you need more voltage (generally) to slow the trailer than to keep it stopped at a stop light, where you won't get 12 volts no matter how hard you press. My guess it that is the reason you don't see high voltage at a stop. The truck knows you are not slowing, just pressing on the pedal at a stop. the slider-lever overrides this measure, and should get you to full voltage even at a stop.

I think! Try it to find out...

 

[jhenderson]

The itbm is partially controlled by the anti lock brakes and also the traction control systems. You won't get full voltage unless you are traveling at a factory pre determined speed. I don't like it either but I doubt Ram cares. Run that same test with your Fluke meter and enough jumper wire to get into the cab. Head down the road at speed and run the test. I had someone reading my meter for safety's sake. You'll get 12 volts initially, then it will lower as you slow down. I have no idea what they were thinking when they came up with this.

 

[gdmercad]

The itbm is partially controlled by the anti lock brakes and also the traction control systems. You won't get full voltage unless you are traveling at a factory pre determined speed. I don't like it either but I doubt Ram cares. Run that same test with your Fluke meter and enough jumper wire to get into the cab. Head down the road at speed and run the test. I had someone reading my meter for safety's sake. You'll get 12 volts initially, then it will lower as you slow down. I have no idea what they were thinking when they came up with this.

Does this apply to the itbm installed in the 2013 RamTrucks?

 

[jhenderson]

I only know about my truck. The trailer brakes are less than desirable and it went back to the dealer the first week. The tech compared it with other trucks on the lot and they all tested the same. They went to Ram and got a load of BS from them. Ram said their controller was fine and the problem was I had analog trailer brakes and the itbm was digital! I have a copy of the E mail to prove it. Did more research and testing and you know my findings.

 

[JDean]

Just to be clear, the lever on the brake controller will give you full braking at whatever gain you have set (not 12v, typically). The gain should be set to lock up or nearly lock up the trailer brakes at about 20 mph per the previous post (no truck braking, just the controller lever). I believe that's the most braking you'll get from the controller, but once the wheels lock up dumping more voltage to the trailer brakes won't help. Pulling the emergency pin on the trailer dumps the max voltage of the trailer battery (and the truck battery if the trailer is still attached) to the brakes. J Dean

 

[jhenderson]

The lever on the itbm will only deliver a max of a little over 7 volts until the factory designated speed is reached. I escalates from that speed on. That is the problem with the itbm programming. As you slow it pulls voltage out whether you use the lever, the foot brake or a combination of both. It's very problematic ( to say the least) when running down hill to an intersection.

 

[mwilson]

Did you check e-trailer.com for a set of those newfangled "Digital Brakes".........???

The tin foil hat that I usually wear would probably block the braking signal and I would run over some poor innocent Amish in a buggy......