Installing Factory Trailer Brake Controller and DIY Software Update

[KMach]

I actually found a tapped wirewound 100 watt resistor (used when building tube amps as an attenuator) . I hooked that up with the meter in series to measure amps. The resistor tap was set to 5 ohms. Most I could get out, on heavy electric setting and gain on 10 was about 1 amp. So is KMach's theory coming into play here? That the truck needs to be moving for it to work properly (or to test)?

Not really my own theory. It is in the description of operation of the TTM and ITBM. They receive many inputs from other modules on the CAN-IHS, CAN-C as well as the TTM having responsibility for its own logic, actuation and sensing.

 

[tyromeo55]

I actually found a tapped wirewound 100 watt resistor (used when building tube amps as an attenuator) . I hooked that up with the meter in series to measure amps. The resistor tap was set to 5 ohms. Most I could get out, on heavy electric setting and gain on 10 was about 1 amp. So is KMach's theory coming into play here? That the truck needs to be moving for it to work properly (or to test)?

I actually found a tapped wirewound 100 watt resistor (used when building tube amps as an attenuator) . Cool find!

I hooked that up with the meter in series to measure amps. The resistor tap was set to 5 ohms. Most I could get out, on heavy electric setting and gain on 10 was about 1 amp.
If it is the old school slider type how many ohms is it total (end to end)? if it is 10 ohms then you can parallel the outside terminals for a total of 2.5 ohms Were you using the dash slider or the brake pedal?

So is KMach's theory coming into play here? That the truck needs to be moving for it to work properly (or to test)? Maybe, cant really say for sure unless you do more testing. My worry is that 5 ohms might not be enough load. Cant rule out the posibility that there might be some sort of protection in play since I dont beleive there is ever a normal situation where it would typically only see a 5 ohm load. It could have a circuit that fluctuates the output current in relation to the sensed load. My curiosity would also need to test more then one truck to get a solid baseline

 

[rutledj]

I set the resistor to 2.5 ohms, wired it up with an amp meter and drove the truck. Got up to 35mph, put on brakes, the most I read was 2.1 amps. This is with the setting on Light Electric with power up to 10. Next I'm going to wire in a Tekonsha Voyager brake control and see if it gives different reading. We had that in our last truck and it worked fine.

 

[tyromeo55]

I set the resistor to 2.5 ohms, wired it up with an amp meter and drove the truck. Got up to 35mph, put on brakes, the most I read was 2.1 amps. This is with the setting on Light Electric with power up to 10. Next I'm going to wire in a Tekonsha Voyager brake control and see if it gives different reading. We had that in our last truck and it worked fine.

That reading is in line with the what you were getting before. 5v sounds pretty low. Out of curiosity I’ll get some 100w resistors and measure my truck. Maybe you got a bad module???

 

[rutledj]

Just tried the Tekonsha controller and got the same results.

 

[rutledj]

Just wanted to throw one more thing out there. When I did the alfaodb part, I chose the my2020 PowerNet. I have a 2021 but I'm assuming 2020 will work. Was this correct?

 

[tyromeo55]

Just tried the Tekonsha controller and got the same results.

Something is wrong. From memory, my truck (2020 DT) has the following while the truck is running without any load attached

any gain 0% about 1V
5.0 gain 50% about 8V
5.0 gain 100% About 10V
10.0 gain 50% over 9V
10.0 gain 100% over 13V

Forgive me but you are testing the bottom two pins right? Did you check any of the other trailer circuits to see if they are getting full volts? Did you check the controller fuse (maybe F1 under the dash). If all thoes things are ok the next place I'd look is the imput side of the trailer outlet on the truck. See if there is proper voltage there

 

[rutledj]

Keep in mind that I'm actually measuring the flow of current through a load, not the voltage. My voltage reading are in line with yours but when I had a camper attached it didn't feel like the camper brakes were engaging, and pressing the slide buttons together, even with a power level of 10, didn't lock up the camper brakes. So my concern is not enough current was getting to the brake magnets. But now that both factory and 3rd party controllers have the same amp reading, I'm assuming it is working. Pick up the new camper on Sat. Will know for sure then

 

[tyromeo55]

Keep in mind that I'm actually measuring the flow of current through a load, not the voltage.
I understand. I don't have any power resistors that get me low enough to do the testing on my truck. The point of the load test is to see if it is required for the controller to give full output. In the interest of help, fun, community I'll get some coming and see what measurements I get off a known working truck. Hopefully that will give everyone here a solid baseline for troubleshooting

Current is only half of the equation. You want to see proper current at the proper voltage. If your only getting 2A with a 2.5 ohm resistor (cold) then there is only 5V at the plug. That is not enough if your sending a 10.0Gain and full pedal. What you should be seeing is about 1V less than charging system volts

Full tilt on a 2.5 ohm resistor id expect near 5AMPS (67watts)
Your seeing 2AMPS (10watts)
That is a LOT LESS power sent to the brakes (nearly 7 times as less)


My voltage reading are in line with yours
No load voltage can seem good when there is no load. As you apply load bad connections take their toll. That is why I suggested it after your initial testing seemed to turn up nothing

when I had a camper attached it didn't feel like the camper brakes were engaging, and pressing the slide buttons together, even with a power level of 10, didn't lock up the camper brakes.
Empty utility trailers aside I would not think you could lock them up anyway. Could you on your last truck setup?

So my concern is not enough current was getting to the brake magnets. But now that both factory and 3rd party controllers have the same amp reading, I'm assuming it is working. Pick up the new camper on Sat. Will know for sure then
I still think something is wrong

 

[rutledj]

It is just interesting that the Tekonsha controller, which I know did work on our 2014 Ram 1500, has the same readings as the factory installed unit on this 2021 1500. It plugs into the factory wiring plug so it is using the same circuitry.

 

[tyromeo55]

It is just interesting that the Tekonsha controller, which I know did work on our 2014 Ram 1500, has the same readings as the factory installed unit on this 2021 1500. It plugs into the factory wiring plug so it is using the same circuitry.

Im sure both controllers are good. Like I said in my post 347. My thoughts...

#1 There is a very slight possibility that the fuse feeding that circuit is bad. I say this because there are a lot of things under the dash that get power from different fuses but share a common ground. As power flows thru all those other device a relative amount of current will flow thru the controller as if it was another conductor in parallel. you get kinda a voltage divider effect which could account for the 5+Volts instead of 12V

#2 there is a bad connection between the controller output and the bumper plug. This would account for a good voltage reading when unloaded and bad as you pull more current. This could also be the most dangerous and damaging if left un addressed.

Just my 2 cents

 

[rutledj]

Your #2 point makes sense. I've seen this before where there is a bad connection. Voltage was good but current not due to corroded contacts on a plug. Not sure where I could find a wiring diagram just for the brake circuit. I suspect hand tracing will be a huge pain.

 

[tyromeo55]

Your #2 point makes sense. I've seen this before where there is a bad connection. Voltage was good but current not due to corroded contacts on a plug. Not sure where I could find a wiring diagram just for the brake circuit. I suspect hand tracing will be a huge pain.

As stupid as it sounds check F1 under the dash. It too east to pull it and check even though pretty darn sure it will be good.

Id imagine that there are not too many joints/connections. Check the one under the bumper B4 it goes into the trailer plug. It is subject to the most weather-damage. its also easy to get to. You could also take it to the dealer if it is under warranty and make it their problem. My resistors are supposed to be here tomorrow. I'll let you know what I see just to make sure I'm not totally crazy

 

[rutledj]

Any luck checking your readings?

 

[tyromeo55]

Any luck checking your readings?

resistors came in and have been sitting on my desk. I need to solder leads on the ends of them and then Ill get to it tomorrow and report back here

 

[nekit]

Anyone know if you can use Alphaobd to enable the trailer light check? I have the factory installed brake controller on my 21’ but didn’t get the full trailering package, that now has trailer light check function. Hoping to add it. Thanks

 

[MannyN]

VehConfig 8, Trailer Light Cycle Present: No
Change to Yes

 

[JDR227]

Thanks everyone for all the good information! The hardware installation was easier then I thought it was going to be and the programming wasn't too bad after reading everything I could in this forum. BTW if anyone needs their truck programmed after installing the brake controller in the Clifton Park, NY area let me know and I let you use my hardware/software to do it.

Thanks Again,
Jay

 

[Txbruin]

Has anyone attempted the install on a 2021 model? I just did the install on my 2021 1500, but when I went to look at the plug that goes into the TBC, it was tape-wrapped next to another, smaller plug. I didn't know where to put this other, smaller plug, as the TBC only had space for the one larger, red plug. Just hoping that this other, smaller plug doesn't need to go in somewhere.

 

[Jocoo26]

Is there anyone on here that has installed a trailer brake switch that would sell me the blank insert panel they removed? I need another one and can’t seem to find this part listed. Is there a separate part number for this blank panel? Thanks