Tow/Haul mode, stuck in 6th gear going up a grade.

[RichM752]

On the way home from a near perfect road trip with the 5th wheel, going up a mild grade in tow/haul mode truck would not drop a gear automatically or manually.
Never experienced this before. Exited the freeway, and all was good. Any ideas what caused this?

 

[Firebird]

That is strange. I've had mine hold 6th going up a steep hill at hwy speeds, and hitting the button down to 5th worked just fine. So when you hit your + - button, nothing happens?

 

[RichM752]

Yep. Never been a problem before, I live in the mountains. Tried the button 4-5 times. Stompted on the pedal a bunch, tired going out of tow/haul.......nada.
Got off the interstate and downshifted fine. Got back on and upshifted fine.
Stopped by the dealer today and the whole place was down. The nice lady told me "the internet was down" so they could not do any business. I instructed her to write my name and number on a piece of paper and call mem when they are back in business.

 

[RichM752]

Appointment was today.
Checked for DTC's, none present.
New software update for PCM with shift improvments listed.
Flashed PCM and preformed quick learn (test drive) as per TSB
That is all.

 

[flan]

Appointment was today.
Checked for DTC's, none present.
New software update for PCM with shift improvments listed.
Flashed PCM and preformed quick learn (test drive) as per TSB
That is all.

Good luck, hopefully it’s the fix you’re looking for!

 

[The1adman]

Appointment was today.
Checked for DTC's, none present.
New software update for PCM with shift improvments listed.
Flashed PCM and preformed quick learn (test drive) as per TSB
That is all.

Do you have the HO/Aisin or SO? I have a 21 3500 HO and have issues with my Tow/Haul actually engaging and locking out 6th gear.

 

[AH64ID]

Do you have the HO/Aisin or SO? I have a 21 3500 HO and have issues with my Tow/Haul actually engaging and locking out 6th gear.

TH doesn’t lock out 6th gear on the Aisin, that’s what ERS is for.

TH does raise the shift points, among other changes, but all 6 gears are still available.

 

[The1adman]

TH doesn’t lock out 6th gear on the Aisin, that’s what ERS is for.

TH does raise the shift points, among other changes, but all 6 gears are still available.

I understand that, but It locks it out below 65 mph. My trucks issue is selecting tow/haul button only works some of the time. If it doesn't work I have to pull over and turn off the truck and once I restart and re-select Tow/Haul it works. When it doesn't work, pulling it lugs in 6th down to 1000 RPM before I can get it to down shift. The point of my question was if there is a PCM or TCM update for the 2021 HO/Aisin.

 

[AH64ID]

I understand that, but It locks it out below 65 mph. My trucks issue is selecting tow/haul button only works some of the time. If it doesn't work I have to pull over and turn off the truck and once I restart and re-select Tow/Haul it works. When it doesn't work, pulling it lugs in 6th down to 1000 RPM before I can get it to down shift. The point of my question was if there is a PCM or TCM update for the 2021 HO/Aisin.

That’s different than locking out 6th, which is what you originally said.

Does T/H light up on your dash?

 

[The1adman]

That’s different than locking out 6th, which is what you originally said.

Does T/H light up on your dash?

That's why I clarified what I meant. Yes, the T/Haul light always lights on my dash when selected, it just doesn't always engage. When it doesn't engage no matter how many times I select and un-select T/H, the only way to get it to engage is to restart the truck. My main purpose of using the T/H is the downshifting combined with the exhaust brake. Not trying to hijack the OP's thread with my issue, but I have a similar 6th gear down shift when it won't engage.

 

[AH64ID]

That's why I clarified what I meant. Yes, the T/Haul light always lights on my dash when selected, it just doesn't always engage. When it doesn't engage no matter how many times I select and un-select T/H, the only way to get it to engage is to restart the truck. My main purpose of using the T/H is the downshifting combined with the exhaust brake. Not trying to hijack the OP's thread with my issue, but I have a similar 6th gear down shift when it won't engage.

I would take it to the dealer and see if there is a reflash or update available, and if not ask them to reload the current software.

 

[dd2500]

Hi Rich,
Same exact thing happened to me. I was sailing along nicely pulling the 7000lb travel trailer up a very slight incline. I came up to some slower traffic and slowed down a little. When I tried to accelerate again it just would not down shift. The +/- buttons would not respond, jamming on the gas pedal would not cause it to down shift. I had to just start pulling over on what was now a narrow road with very little shoulder. As cars were now passing me and I got slow enough it suddenly would down shift again like normal. At that point I just kept going.

This was about 6 months ago, hasn’t happened in several tow trips since.

When you went to the dealer, did they acknowledge that the update would address this? Or was it just a try it and see what happens kind of thing?

Thanks, hope yours is fixed.

 

[RichM752]

Hi Rich,
Same exact thing happened to me. I was sailing along nicely pulling the 7000lb travel trailer up a very slight incline. I came up to some slower traffic and slowed down a little. When I tried to accelerate again it just would not down shift. The +/- buttons would not respond, jamming on the gas pedal would not cause it to down shift. I had to just start pulling over on what was now a narrow road with very little shoulder. As cars were now passing me and I got slow enough it suddenly would down shift again like normal. At that point I just kept going.

This was about 6 months ago, hasn’t happened in several tow trips since.

When you went to the dealer, did they acknowledge that the update would address this? Or was it just a try it and see what happens kind of thing?

Thanks, hope yours is fixed.

They did not mention anything about problem has been fixed, only that software was updated. And a "let us know if you have anymore issues".
As I side note, I never mentioned anything about "shifting weird", and explained to them in detail how the problem of sticking in 6th gear was on only one occasion.
I haven't towed anything since, Dec 13 when we put the 5th wheel in storage, and haven't had a reason to use my equipment trailer.