Downshifting into MANUAL from 50mph

[Retired Bob]

While the truck is sitting still I can understand shifting into MANUAL instead of 'D' and then using the +/- button to select, say, 5th gear and then driving with the transmission upshifting and downshifting between 1st and 5th (but not 6th gear) as usual.

 

Can I shift to MANUAL while the truck is doing, say, 50mph in 'D'? I'm guessing I can, but does shifting into MANUAL still require me to use the +/- selector to select a gear? Or would the transmission automatically go into the best gear for the speed and load at 50mph?

 

Sitting still, I select 5th gear in MANUAL but at 50mph shifting into MANUAL certainly would not require me to use the +/- button to select 5th gear would it - it would automatically go right into 5th gear wouldn't it and continue to upshift/downshift as necessary?

 

Never had a vehicle that allowed me to select a MANUAL mode and the Owner's Manual is light on usable instructions.

[Adleeper]

When switching into manual mode from any speed it goes to the current gear you are in and then is selectable with the + / -

[JRDUCKS]

When switching into manual mode from any speed it goes to the current gear you are in and then is selectable with the + / -

Not technically true...if you are in gear 5 or 6 when you put it into manual mode it will shift to gear 4. I believe the rest are basically a decrease by one so if you're in gear 4 shift to manual mode you'll go to gear 3...in 3 you'll go to 2 and then 2 goes to 1.

[Retired Bob]

So, if I'm going 70mph down the Interstate (in 'D' or 6th gear) and I move the shift knob from 'D' to MANUAL on the fly, the transmission would just downshift to 5th gear (as MANUAL is only gears 1-5) and then work normally?

[redwngr]

So, if I'm going 70mph down the Interstate (in 'D' or 6th gear) and I move the shift knob from 'D' to MANUAL on the fly, the transmission would just downshift to 5th gear (as MANUAL is only gears 1-5) and then work normally?

The way the chart in the owners manual reads, it would shift to M4. page 9-35/36 of the 2015 manual

[KARNUT]

You can hit manual at any speed and upshift at will, when you down shift it will rev match, pretty cool. I run in M5 most of the time until I go over and stay over 60. Im a hands on driver so when I pass I do most of my own shifting. I wish these trucks came with manual trans.

[redwngr]

If it matters, grade braking function does not work in manual.

 

Manual mode also does not prevent the transmission from downshifting, it only limits the maximum gear that it can select.

[Silverado-Hareek]

In my experience, when I shifted to M, it went to the gear I was already in while the truck was in drive. So if it was in 5th gear, shifting to M put the truck in M5. Are you saying I was actually in 6th gear and when I switched to M, it shifted down to M5? I don't recall if it was in 6th gear or not when I shifted to M but I seem to remember getting the impression that it went to the gear I was already in while in drive.

[redwngr]

Here's the chart from the 2015 manual:

 

Gear before shifting from D (Drive) to M (Manual Mode) 6th 5th 4th 3rd 2nd 1st

Range after shifting from D (Drive) to M (Manual Mode) M4 M4 M3 M2 M2 M1

The manual suggests that it shouldn't ever go directly to M5

[bboyce536]

When shifting into manual mode it will shift into 4th gear if above 4th no matter what. Even if you are going 80mph it will downshift to 4th. But otherwise in town when in 1st-4th when you shift it from D to M it will just say in the current gear you're in.

 

Edit:see the chart above...good to know. I always thought below 4th it stayed in the current gear.

[redwngr]

I wonder what the 8 speed is going to do??

[Retired Bob]

From the manual:

"In vehicles with gasoline engines,
when the shift lever is moved from
D (Drive) to M (Manual Mode), a
downshift may occur. The gear that
the transmission is operating in
when the shift lever is moved from
D (Drive) to M(Manual Mode)
determines if a downshift occurs.
See the following chart."

 

Gear before shifting from D(Drive) to M (Manual Mode)
6th 5th 4th 3rd 2nd 1st
Range after shifting from D(Drive) to M (Manual Mode)
M4 M4 M3 M2 M2 M1

 

Edit: Dup from above - posted before I read above.

[02suburbanZ71]

I like the 6 speed because i can shift it at 6K.... Sounds mean

[redwngr]

I wonder what the 8 speed is going to do??

Can across the 8 speed info today. The (Manual) gear that the 8 speed switches to depends on if it is in tow/haul or not.

 

8–Speed Automatic Transmission

Gear before shifting from D (Drive) to M (Manual Mode) 8th 7th 6th 5th 4th 3rd 2nd 1st

Range after shifting from D (Drive) to M(Manual Mode)

– Tow/Haul not engaged M6 M6 M5 M4 M3 M3 M2 M1

– Tow/Haul engaged M6 M5 M4 M3 M3 M3 M2 M1

Grade braking is not available in manual mode (range selection mode).

Tow/haul will still operate.

+/- buttons can be used to select any maximum gear (including 7 and 8)

[Brandon Thompson]

I have found that while in manual shift. It stays in V8 mode and does not got to V4 which I like better because now I know 100% of my engine is getting used. There is been a lifter problem around 100k due to the fact that half of them only get used half he time.