2020 HO 3500 SRW Aisin issue

[larryq]

This has been happening since day one. Now 20,000 miles in, I think it’s time to ask.

sometimes, when warm or cold engine temps, I will come into the neighborhood, doing 20-25 mph.
Stopping at stop signs or going around a corner without any “gas pedal”.
Then go to accelerate, and the transmission has dropped out of first, into neutral.

Hit the go pedal and rpm comes up and then BANG into first.

I know this transmission has always had issues with stop and go traffic, but there has to be a new program to correct this.

have an 8 year 150,000 mile warranty, and tomorrow the new High pressure fuel pump is being installed and the CP4 will be gone.

I think I’ll call tomorrow and have them look at the transmission and see if there is a new update.

It happens often enough to make me concerned.
Any thoughts???

Thanks@All

l

 

[Tuesdak]

They haven’t figured this out. My 2018 does the same thing with all the updates. My favorite is starting from a complete stop and it’s finally able to shift resulting in a cargo shifting jerk. I give up on easy starts as it randomly doesn’t let me…

You will learn the “drive around” the 2-Neutral-1 slam shift.

Just know if the dealer resets the learning on the transmission it takes 1000 miles of tire screaming shifts to figure itself out. Say if you catch a green light on a roll.


https://www.turbodieselregister.com/threads/2018-ram-6-7-cummins-aisin-whos-on-first.269679/

 

[Timd32]

There is one TSB that is 2020 3500 related to poor shift quality. They never really say what the exact fix is on these.

Sometimes these are rolled into other updates you may have received.

TSB are sometimes VIN specific as well and this might not apply to your truck.

21-003-21

 

[larryq]

They haven’t figured this out. My 2018 does the same thing with all the updates. My favorite is starting from a complete stop and it’s finally able to shift resulting in a cargo shifting jerk. I give up on easy starts as it randomly doesn’t let me…

You will learn the “drive around” the 2-Neutral-1 slam shift.

Just know if the dealer resets the learning on the transmission it takes 1000 miles of tire screaming shifts to figure itself out. Say if you catch a green light on a roll.


https://www.turbodieselregister.com/threads/2018-ram-6-7-cummins-aisin-whos-on-first.269679/

That’s exactly the thing…2-neutral-1 slam shift!

Couldn’t have described it better!

I am worried with 1K torque that SLAM is going to eventually tear stuff up!

Even though i have an 8Y-150,000 warranty, id prefer not to break stuff!

Thanks!

 

[AH64ID]

Interesting, never noticed this on my ‘18 or dads ‘17. I guess we’ll see what happens when my ‘22 decides to show up.

 

[bcbender]

haven't experienced this in 22k miles yet.. I'll keep my fingers crossed its unit specific.

 

[Wiredawg]

There's plenty of discussion about the Aisin's 1 to 2 shifts being harsh. I had an Aisin in my 09 4500 and have one in my 17 5500 and occasionally experience something similar. I pretty much write it off to Aisin programming related to high torque at low RPMs. Another thought is a delay between the ECM and Trans controller. C&Cs a little different in power curves on the Cummins and programming on the Aisin, but still seems to be more noticeable to some than others. My friends 22 Duramax SRW 3500 is smooth as silk.

 

[Tuesdak]

I am worried with 1K torque that SLAM is going to eventually tear stuff up!

It's NOT shifting at full power. It's already "pulled the power back" in torque management otherwise, yes, it would embed hot oily parts in the road.

It appears to simply go into Neutral and stay in Neutral if it screws the shift up badly enough. Rolling a light I have had the tires screech during the 1000 mile re-learn (I assume it held two gears at once and locked up for a moment) and then I watch the engine at redline until I remove my foot from the throttle. IMO it's binding up and unable to release the current gear or release it fast enough esp. when a serious grade is reducing MPH quickly. Or the coordination between the transmission ECM and engine ECM is out of range for a shift.

Serious grade: is like the backup sensors going off from the road below backing out of my driveway where the video done.

The Allison is the same thing, but, say has dog slow shifts. I had a 2005 'tuned' to speed up the shifts at the risk of locking up or dragging between shifts. When you tune the shift speed you understand how slow it was at shifting. IDK if GM has speed up the shifting on the newer ones.

 

[Tuesdak]

Interesting, never noticed this on my ‘18 or dads ‘17. I guess we’ll see what happens when my ‘22 decides to show up.

I an starting to suspect there is a production variance of some kind where some do not have the shifting problems and others do. This may NOT be limited to the transmission as torque management requires the engine to throttle down. We have compared some notes and have differences for example my engine 'blips' the throttle due to rail pressure* after I release the throttle. It also has a 'bog' a moment after applying power.

*Dealer claimed this and said it was the same as another one they drove to compare.

The updates have made a huge difference in the shifting esp. the 1-2 shift.

 

[larryq]

Since the truck is currently having the high pressure fuel pump recall being done, I called and told them about the 2-1 slam and asked if they could check to see if the TPM might have an update to address the issue.

Never hurts to ask, especially while they already have the truck.
Thanks to everyone who contributed!
L

 

[tron1959]

Turn off “Hill Start Assist” that may help.

 

[Tuesdak]

Turn off “Hill Start Assist” that may help.

Done long ago and it did help.

 

[larryq]

Picking the truck up tonight after the high pressure fuel pump recall.

they also updated the tpm and had to put it back to re learn.

we shall see what’s what.

 

[larryq]

Had the truck in for the HPCR fuel pump recall.
I asked about a tpm update, and sure enough there was one.

The transmission is still in “learn” mode, but the shifts are vastly improved!

The only weird” thing, is that from p to d, or p to r, there is a delay.

Kinda like an old 70s transmission, low on fluid.

Hard to explain, but its a noticeable change.

Ill take it if it fixes the 2-1 SLAM!
L

 

[NIsaacs]

The only weird” thing, is that from p to d, or p to r, there is a delay.

Kinda like an old 70s transmission, low on fluid.


L

My 68RFE does that once in a great while, like it is in neutral, bugs me...

 

[Joseph Donnelly]

I have never had this issue with my 2013 in 55,000 miles.