Question about D and M....
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Tuned
Joined: Dec 2018
Posts: 330
Likes: 26
Question about D and M....
I hated that Duramax, but I loved the Allison transmission...especially the Manual feature. When M is selected with the lever, you can use the + to select the HIGHEST gear you want to use. When you drive away, it starts out in 1, then shifts to 2 as your speed increases.....all the way to the gear you selected, effectively locking out the rest.
I thought it would be the same with the 6R140, but apparently I was wrong.
According to the manual: "The SST will not automatically upshift, even if the engine is approaching the RPM limit. It must be shifted manually by pressing the + button."
So my question is: How do I "lock out" a gear from being used?
The manual further says:
"With the gearshift lever in D (Drive), press the – button to active SST. The available and selected gears will be indicated on the instrument cluster.
All available gears will be displayed with the current gear indicated.Press the – button again to lock out gears beginning with the highest
gear. Example: press the – button twice to lock out 6th and 5th gears.
Only the available gears will be displayed and the transmission will automatically shift between the available gears. Press the + button to unlock gears."
This contradicts what it just said!
Pages 293 and 294 of the owner's manual...
When I'm putting through town, I don't need the truck to shift into 6th and lug along at 500 RPM.But unless I use T/H mode, it will continue to upshift until I run out of gears.
Likewise when I'm hauling...I know that OD puts a lot of strain on the tranny as well as build up heat so I'd rather not use 6th, even at highway speeds.
So far, the only work around I've found seems to be using T/H mode.
So that would be another question....Is it OK to use Tow/Haul mode all the time?
I thought it would be the same with the 6R140, but apparently I was wrong.
According to the manual: "The SST will not automatically upshift, even if the engine is approaching the RPM limit. It must be shifted manually by pressing the + button."
So my question is: How do I "lock out" a gear from being used?
The manual further says:
"With the gearshift lever in D (Drive), press the – button to active SST. The available and selected gears will be indicated on the instrument cluster.
All available gears will be displayed with the current gear indicated.Press the – button again to lock out gears beginning with the highest
gear. Example: press the – button twice to lock out 6th and 5th gears.
Only the available gears will be displayed and the transmission will automatically shift between the available gears. Press the + button to unlock gears."
This contradicts what it just said!
Pages 293 and 294 of the owner's manual...
When I'm putting through town, I don't need the truck to shift into 6th and lug along at 500 RPM.But unless I use T/H mode, it will continue to upshift until I run out of gears.
Likewise when I'm hauling...I know that OD puts a lot of strain on the tranny as well as build up heat so I'd rather not use 6th, even at highway speeds.
So far, the only work around I've found seems to be using T/H mode.
So that would be another question....Is it OK to use Tow/Haul mode all the time?
Hotshot
Joined: Oct 2006
Posts: 10,154
Likes: 7,984
From: Texas
I hated that Duramax, but I loved the Allison transmission...especially the Manual feature. When M is selected with the lever, you can use the + to select the HIGHEST gear you want to use. When you drive away, it starts out in 1, then shifts to 2 as your speed increases.....all the way to the gear you selected, effectively locking out the rest.
I thought it would be the same with the 6R140, but apparently I was wrong.
According to the manual: "The SST will not automatically upshift, even if the engine is approaching the RPM limit. It must be shifted manually by pressing the + button."
So my question is: How do I "lock out" a gear from being used?
The manual further says:
"With the gearshift lever in D (Drive), press the – button to active SST. The available and selected gears will be indicated on the instrument cluster.
All available gears will be displayed with the current gear indicated.Press the – button again to lock out gears beginning with the highest
gear. Example: press the – button twice to lock out 6th and 5th gears.
Only the available gears will be displayed and the transmission will automatically shift between the available gears. Press the + button to unlock gears."
This contradicts what it just said!
Pages 293 and 294 of the owner's manual...
When I'm putting through town, I don't need the truck to shift into 6th and lug along at 500 RPM.But unless I use T/H mode, it will continue to upshift until I run out of gears.
Likewise when I'm hauling...I know that OD puts a lot of strain on the tranny as well as build up heat so I'd rather not use 6th, even at highway speeds.
So far, the only work around I've found seems to be using T/H mode.
So that would be another question....Is it OK to use Tow/Haul mode all the time?
I thought it would be the same with the 6R140, but apparently I was wrong.
According to the manual: "The SST will not automatically upshift, even if the engine is approaching the RPM limit. It must be shifted manually by pressing the + button."
So my question is: How do I "lock out" a gear from being used?
The manual further says:
"With the gearshift lever in D (Drive), press the – button to active SST. The available and selected gears will be indicated on the instrument cluster.
All available gears will be displayed with the current gear indicated.Press the – button again to lock out gears beginning with the highest
gear. Example: press the – button twice to lock out 6th and 5th gears.
Only the available gears will be displayed and the transmission will automatically shift between the available gears. Press the + button to unlock gears."
This contradicts what it just said!
Pages 293 and 294 of the owner's manual...
When I'm putting through town, I don't need the truck to shift into 6th and lug along at 500 RPM.But unless I use T/H mode, it will continue to upshift until I run out of gears.
Likewise when I'm hauling...I know that OD puts a lot of strain on the tranny as well as build up heat so I'd rather not use 6th, even at highway speeds.
So far, the only work around I've found seems to be using T/H mode.
So that would be another question....Is it OK to use Tow/Haul mode all the time?
To lock out upper gears. Simply press the - button on the stalk WHILE IN D.....one time locks out 6th, two times locks out 5th and 6th, three times locks out 4th, 5th and 6th. DO NOT USE “M” IF YOU WANT THE TRANSMISSION TO SHIFT ITSELF. No need to use T/H unless you just want to.
Post Fiend
Joined: Nov 2001
Posts: 6,748
Likes: 118
From: Tallassee, ALabama
You can lock out a gear(s) when in normal or tow/haul by pressing the minus (-) button. I normally do this when towing in the mountains. I can manually downshift also, forcing it to go to a lower gear. As the road levels out some, I press the plus (+) button to add gear(s) back. When out of mountains, I press the plus(+) to add all back.
Laughing Gas
Joined: Nov 2012
Posts: 1,169
Likes: 29
From: Bismarck, ND
You "can" use T/H all the time, if you want. Sounds like just using D and locking out upper gears is what you're looking for. As others said, just shift into D, then start pressing the "-" button. First press will "light up" the gear shift indicator (if it isn't already, I normally have mine switched off when driving unloaded). Then each time you press the "-" button, it disables the next highest gear. I think you can go down to "3".
When I'm pulling heavy, I use Manual mode. Shift to "M" and then just use "+" and "-" to upshift and downshift. Love that mode.
I almost never use T/H. It's either in "D" for normal daily driving, or "M" for hauling heavy.
Enjoy.
When I'm pulling heavy, I use Manual mode. Shift to "M" and then just use "+" and "-" to upshift and downshift. Love that mode.
I almost never use T/H. It's either in "D" for normal daily driving, or "M" for hauling heavy.
Enjoy.
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