No Trailer brake voltage

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Ram24

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I have a 2015 2500 (6.4hemi). I am not getting any voltage to the trailer brakes. It has ITBM. I have checked all fuses under the hood. Do not see or know of any fuses in cab. All lights work perfectly fine and trailer brakes work fine when hooked to other vehicles. (06 2500 and a 20’ 3500 with ITBM). Ground seems to be fine. 12v to the constant power post and charging trailer battery but none on the eletric brake post when manually squeezing or stepping on pedal ( yes the gain has been adjusted from 0-10 and everywhere in between). I have switched from light electric to heavy and even tried the other two options with no change. It doesn’t seem to be recognizing the trailer as dash reads “not connected”. Anybody ran into this? Bad module possibly? Called two dealers with very few ideas on what’s going on and closest one is 1.5 hrs away. I have a gooseneck trailer on that has drum style brakes. Am going to try another trailer tomorrow but I’m positive it’s not the trailer as brakes are working on everything else. Thanks!
 

chopperman1

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OEM trailer brakes are a pulse modulated setup. You will not get the traditional 12v with them. With a high quality meter you mat be able to catch the pulses with a peak hold but you'd be lucky to catch 6-8v maybe. They do make trailer brake simulators but they are rather pricey.
 
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Ram24

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I have a fluke meter that is working to read voltage on every other pickup I’ve checked while trying to figure this out which is 7 different pickups. But you can also hear and also showing up on displays that brakes are applying when hooked on something else which I’ve had it on two others while testing.
 

BossHogg

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I have a fluke meter that is working to read voltage on every other pickup I’ve checked while trying to figure this out which is 7 different pickups. But you can also hear and also showing up on displays that brakes are applying when hooked on something else which I’ve had it on two others while testing.
As chopperman1 said, the trailer brake circuit is pulse width modulated, basically a series of 12-volt pulses within a period of 250 milliseconds. While Fluke is an outstanding meter, it also has a sampling period. Depending on the frequency the meter samples versus when the brake circuit has a high pulse will yield an average voltage, usually 7 volts or more when the trailer brake controller's slider is pushed to its limited travel. Checking other trucks isn't helpful unless you know if the other trucks have the same type of brake controller as your 2015.

The factory trailer brake senses if a trailer is connected by looking for an inductive load on the electric brake pin. If the trailer doesn't have electric brakes, the ITBM will not sense a trailer. If you don't have access to a trailer brake simulator, the simplest test is to connect a 12-volt electric motor to the brake circuit and see if the ITBM will vary the motor's speed (note that a filament light bulb is not an inductive load).

With the info you provided, it appears the ITBM isn't working which is unlikely, I'm assuming your brake controller is factory. Your best bet (and least expensive) to find the root cause is to try a 12-volt DC motor on the brake circuit or invest in a brake simulator like the one below. When used manually, using the ITBM slider, the ITBM will output a brake signal regardless if a trailer is connected. I have a 2015 RAM HD with the factory brake controller and have invested time in solving trailer brake issues. It was painful but I did invest in one of these;

 

crash68

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I believe the HD trucks use the same fuse layout as the 1500s, double check the F11 fuse as that is the one for the trailer brake output. The other fuse is the F87 for the ITBM.
I'd check the connection to the brake module under the dash(it's separate from the slider on the dash). Also people have had issues with the trailer plug on the bumper, pull the plug out from the back and check for voltage and connection. Another reported failure area is where the wiring harness runs around the frame area just behind the front wheel (the wheel well liner needs to be pulled).
If it does come down to a bad module, being a '15 has it's quirks. The brake module is specific the model year, the kit part number: 82214492AB
 

zrock

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Their is another fuse in the system that is not marked but controls the trailer brake.. On my truck it was ties to a air suspension fuse that i had removed when i deleted air suspension, im assuming a non air suspension truck may have it tied to another fuse that is not marked..
 
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Ram24

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I guess I should have hooked on a different trailer before I made the post but 2 other trailers are working perfect so it must be a trailer issue. Only thing that still throws me is it’s only this 15 that it is not working on. Will do some more looking on the trailer not sure where to even start. we just replaced a couple magnets and it’s worked fine on other vehicles! And them two sets out of 4 are working! Thank you guys!
 

BossHogg

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I guess I should have hooked on a different trailer before I made the post but 2 other trailers are working perfect so it must be a trailer issue. Only thing that still throws me is it’s only this 15 that it is not working on. Will do some more looking on the trailer not sure where to even start. we just replaced a couple magnets and it’s worked fine on other vehicles! And them two sets out of 4 are working! Thank you guys!
It might be a 7-pin connector issue and the RAM. There seems to be several 7-pin connector designs (connector internals), some much better than others. One test you could do is pull the trailer's safety brake-away switch and try pulling the trailer to see if there is resistance due to full braking. Be sure the trailer's battery is fully charged and do not leave the switch pulled any longer than to run the test to prevent overheating the electromagnets. Issues like this are usually rooted in intermittent grounds or a trailer brake wire shorting to ground.

The 2015 model year and the ITBM had an interesting issue. 2015s built before November of that year had an issue where the ITBM would significantly back off on the amount of energy being sent to the trailer's brakes (destroying the theory of proportional braking). The first time I noticed this (my 2015 was built in March of 2015) was when I had a last-minute traffic light change while pulling 16K of RV and I discovered when the truck fell below 30 MPH, I lost my trailer braking. I was pushed into the intersection, fortunately, there was no cross traffic.

After many complaints and others on the various RAM forums expressing the same, RAM released an update for the ITBM and the ABS module in November 2015. That fixed the trailer braking issue. I don't think this update has anything to do with not recognizing a trailer with brakes but it is an issue you should be aware of.
 

markabby

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i kept getting that message on my truck when the trailer was hooked up. I thought the 7 pin connector was messed up, but i traced it back to a bad wire on the brake magnets. They're in a series, so.....if a wire is bad, they're all bad ( on my trailer)
 

2003F350

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There's not as many regulations and standards on building trailers as there are on passenger vehicles/trucks. Which is why there are several different designs for plugs.

I had an issue with my flatbed on my '17, it would sometimes have brakes and all lights, other times only one tail light and no brakes. It worked fine behind my wife's Ford at the time. However, my '17 had no issues with our travel trailer or any other trailer.

After investigation, I found that the plug on the flatbed had just a flat blade style in the 7-way round, while our travel trailer and several others had what I call 'spring' style - they had multiple blades that tapered and touched when disconnected. I put one of these on my flatbed and the brake issue went away - had brakes 100% of the time. The light issue turned out to be a bad ground at the rear tail light, replaced them with LED housings and ground down to good metal to ensure a good ground. Now have no issues with the trailer.

Basically it boils down to this: Make sure you've got good components, and you'll probably have to pay more for them, but once you have them installed correctly things should work as expected.
 
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