2020 Trail boss DFM shudder

Pinnacle · January 2, 2021

On 4/15/2020 at 2:52 PM, Therealnpp said:

Just wondering if anyone else has had this problem. I have a 2020 TB LT with the 5.3 and 10 speed and I keep getting a really bad shudder at low speeds. Specifically 27-40mph (sometimes higher) when I'm steady state driving and just begin to tip into the throttle. It's at the dealer now and they have confirmed and are firing an ECM at it, but I'm always skeptical about ECM "fixes"

Hoping other people can chime in with similar problems or no problems. I'm hoping this isn't just poor design and something can actually be fixed.

Ram has tried to address this with counter balance weights on the frame and its worked, GM hasnt and its been a problem since the NNBS, whenever AFM/DFM is on.

wacnstac · January 23, 2021

On 12/20/2020 at 8:06 PM, SilveradoTB217 said:

I'm having this exact same issue in my 2020 Trailboss with the 5.3. The shudder happens after the truck is in top gear and DFM is activated, then you apply very light tip of the throttle and it feels like you just drove over a section of rumble strips until the truck drops to a lower gear. My truck is going back to the dealer tomorrow. I had it at the dealer for the last 2 weeks and they replaced the torque converter. After I picked it up this past Friday, I got a mile down the road and the issue still occurred. I've got 18k miles on my truck and it didn't start getting bad until about 15k. Now I have what seems to be a driveline vibration that's stemming from the DFM acting up.
Can you give me an update on what the dealer ended up doing on your truck? I'm going back to my dealer tomorrow morning.

Were they able to fix your issue? I'm now having the same exact problem on my 2020 TB with about 13,000 miles on it.

wacnstac · January 23, 2021

On 4/17/2020 at 1:49 PM, Therealnpp said:

In regards to the DFM and different modes, I'm aware. What I am saying is the speed and time at which it shudders changes. The shudder is exact at certain moments when the DFM is functioning but the shudder moves to different speeds based in the mode I'm in because the transmission shifts are now different. The DFM in these trucks is pulse width modulated through the use of the torgue converter. My initial thought was the TC was locking up at slow speeds, but according to the technician, the transmission was working the way it should. He effectively noted that the shudder was happening at the same time the DFM was activating.

Yes, I'm skeptical of the ECM because they rarely fix anything, but they have in the past. So, we'll see. It's at least a starting point.

But based on the number of views this post has had, it doesn't appear that there are many people who are having similar experiences, which leads me to believe it can be fixed.

There is also a TSB out for exactly what I am experiencing.

I also want to add that the torque put out through a diesel will be vastly different than a gas engine. My concern is very specifically occuring right at 27mph when I am not on the throttle and just barely tip back into the throttle. Which also leads me to believe that the truck is in DFM mode and is not properly coming out of DFM mode.

I appreciate your feedback, though. Thank you for taking the time to respond.

What is the TSB number? Did they ever fix your issue? I am having the same issue with my truck. My first issue was a leaky transmission which started day 1.

RWTJR · January 23, 2021

On 12/30/2020 at 8:06 PM, 14SLE said:

I had a Range unit for my old truck that is on its way in for an update to the newest version right now. I will be curious to see how it works on the '20 truck and what effect it has on fuel economy. I probably won't use it much unless the DFM system gets more obnoxious over time.

I did the same thing. I had my Range unit updated for my new truck and haven't even plugged it in yet. So far, I haven't even noticed the DFM.

RWTJR · January 23, 2021

On 12/20/2020 at 8:32 PM, Therealnpp said:

The dealer replaced the valve body in the transmission. I’ve got 5100 miles on it now and it has been great ever since.

So the dealer said, it's the DFM, we're going to fix it through the ECM, and according to the technician the transmission was working as it should. Yet, they replaced the transmission valve body. Am I understanding this correctly?

Therealnpp · January 23, 2021

Correct. But they only replaced the valve body after the ECM didn’t do the trick. I was told by the service advisor that GM contacted them and told them to replace the valve body.

Therealnpp · January 23, 2021

5 hours ago, wacnstac said:

What is the TSB number? Did they ever fix your issue? I am having the same issue with my truck. My first issue was a leaky transmission which started day 1.

I don’t recall the TSB number but the ECM never fixed the problem. They ended up replacing the transmission valve body per GM and that did fix it.

Therealnpp · January 23, 2021

33 minutes ago, RWTJR said:

So the dealer said, it's the DFM, we're going to fix it through the ECM, and according to the technician the transmission was working as it should. Yet, they replaced the transmission valve body. Am I understanding this correctly?

Correct. But they only replaced the valve body after the ECM didn’t do the trick. I was told by the service advisor that GM contacted them and told them to replace the valve body.

14SLE · January 24, 2021

23 hours ago, RWTJR said:

I did the same thing. I had my Range unit updated for my new truck and haven't even plugged it in yet. So far, I haven't even noticed the DFM.

There are definitely times when I can tell DFM is active (rumble, vibration, etc.), particularly at low speeds. Fortunately, I have not started to hate it yet. The only options for full-sized trucks nowadays are: 1) Poor fuel economy (Toyota, Nissan), 2) Small engines with turbos (Ford), or 3) Messing around with variable displacement (GM, Ram). I have heard rumors that Toyota will be joining the turbo club on the upcoming Tundra (3.5L V6 with twin turbos). The use of adaptive ("learning") computer control can also cause issues because changing shift points and fuel delivery parameters can change resonant frequencies. As a software engineer, I honestly believe the "learning" capability is what ruined my 2014 GMC truck with AFM because the truck drove fine when I bought it. My drive to work has several long straight stretches where the speed limit is 35 mph and the truck began getting more and more aggressive at switching to V4 on those stretches even though it was lugging all the way. The dealership said it had "learned' my driving habits--I asked them to reset the system, but they couldn't (or wouldn't). I had to use the Range device or the truck was almost unbearable. There were certain RPM and speed combinations where the 2014 would vibrate loudly and those seemed to change over time. Using the Range device stopped the problems at the expense of fuel economy (around 2 mpg for me). Honestly, the AFM system wouldn't have been bad if it had only activated above about 45 mph. I could have set the minimum activation speed via tuning, but that risked my extended warranty. I am hoping the DFM system doesn't become as objectionable as the AFM system became. If it does, I will use the updated Range device until I decide what vehicle to get next.

For those of you who are having vibration problems, the Range device is a good way to see if AFM/DFM is causing them without risking your warranty. If you plug in the device and your problems go away, it's probably the AFM/DFM system.

HondaHawkGT · February 10, 2021

On 1/1/2021 at 6:31 PM, Pinnacle said:

Ram has tried to address this with counter balance weights on the frame and its worked, GM hasnt and its been a problem since the NNBS, whenever AFM/DFM is on.

Ram put vibrating electric motors on the frame that will inevitably die a corroded death after a few years of exposure to road salt, and will no doubt cost several hundred dollars to replace with new genuine Mopar vibrators. Kind of like their air ride system solved the squat issue with their trucks, but created a bunch of new reliability issues as the system has a reputation for failing and being quite expensive to fix.

Edited February 10, 2021 by HondaHawkGT

HondaHawkGT · February 10, 2021

On 4/15/2020 at 2:52 PM, Therealnpp said:

Just wondering if anyone else has had this problem. I have a 2020 TB LT with the 5.3 and 10 speed and I keep getting a really bad shudder at low speeds. Specifically 27-40mph (sometimes higher) when I'm steady state driving and just begin to tip into the throttle. It's at the dealer now and they have confirmed and are firing an ECM at it, but I'm always skeptical about ECM "fixes"

Hoping other people can chime in with similar problems or no problems. I'm hoping this isn't just poor design and something can actually be fixed.

Mine would on rare occasion go into a deactivation pattern at very light throttle between 25 and 45 MPH that would have noticeable vibration. The odd thing is, it only does it when I use 87 octane ethanol blend gasoline. When I run 91 octane pure gasoline, it never seemed to do it. So I just run 91.

Edited February 10, 2021 by HondaHawkGT

Pinnacle · February 11, 2021

42 minutes ago, HondaHawkGT said:

Ram put vibrating electric motors on the frame that will inevitably die a corroded death after a few years of exposure to road salt, and will no doubt cost several hundred dollars to replace with new genuine Mopar vibrators. Kind of like their air ride system solved the squat issue with their trucks, but created a bunch of new reliability issues as the system has a reputation for failing and being quite expensive to fix.

no

HondaHawkGT · February 11, 2021

2 hours ago, Pinnacle said:

no

Dodge was putting those on truck frames since the mid-2000's. They are not particularly good at canceling out vibration from an engine with deactivated cylinders. Hydraulic engine mounts and cab mounts help a lot more.

Ram uses vibrators to cancel out MDS vibration:

Despite both attempts, you'll still see plenty of Ram owners complaining about MDS vibration. Some even disabled the active vibrators and had vibrations go away.

Edited February 11, 2021 by HondaHawkGT

SSsierra · February 12, 2021

On 1/24/2021 at 2:34 PM, 14SLE said:

There are definitely times when I can tell DFM is active (rumble, vibration, etc.), particularly at low speeds. Fortunately, I have not started to hate it yet. The only options for full-sized trucks nowadays are: 1) Poor fuel economy (Toyota, Nissan), 2) Small engines with turbos (Ford), or 3) Messing around with variable displacement (GM, Ram). I have heard rumors that Toyota will be joining the turbo club on the upcoming Tundra (3.5L V6 with twin turbos). The use of adaptive ("learning") computer control can also cause issues because changing shift points and fuel delivery parameters can change resonant frequencies. As a software engineer, I honestly believe the "learning" capability is what ruined my 2014 GMC truck with AFM because the truck drove fine when I bought it. My drive to work has several long straight stretches where the speed limit is 35 mph and the truck began getting more and more aggressive at switching to V4 on those stretches even though it was lugging all the way. The dealership said it had "learned' my driving habits--I asked them to reset the system, but they couldn't (or wouldn't). I had to use the Range device or the truck was almost unbearable. There were certain RPM and speed combinations where the 2014 would vibrate loudly and those seemed to change over time. Using the Range device stopped the problems at the expense of fuel economy (around 2 mpg for me). Honestly, the AFM system wouldn't have been bad if it had only activated above about 45 mph. I could have set the minimum activation speed via tuning, but that risked my extended warranty. I am hoping the DFM system doesn't become as objectionable as the AFM system became. If it does, I will use the updated Range device until I decide what vehicle to get next.

For those of you who are having vibration problems, the Range device is a good way to see if AFM/DFM is causing them without risking your warranty. If you plug in the device and your problems go away, it's probably the AFM/DFM system.

Did anyone try the range or the pulsar or see if it cures the low speed shutter with the 10 spd

Pinnacle · February 13, 2021

On 2/10/2021 at 9:00 PM, HondaHawkGT said:

Dodge was putting those on truck frames since the mid-2000's. They are not particularly good at canceling out vibration from an engine with deactivated cylinders. Hydraulic engine mounts and cab mounts help a lot more.

Ram uses vibrators to cancel out MDS vibration:

Despite both attempts, you'll still see plenty of Ram owners complaining about MDS vibration. Some even disabled the active vibrators and had vibrations go away.