2017 Sierra HD PRNDL 1 question

SierraHD17 · September 25, 2017

None of the GM trucks show what gear it's in... if thats the case it will move up and down with the shifts. Like put it in M5 and then come to a stop... it still says M5 and will upshift to 5th gear and not into 6th. My 2015 LTZ Chev did this as does my 2017 SLE.

That said the "1" setting is to lock the transmission into first. If you shift it into "1" while you are at cruise the truck will downshift as low as it can safely go in an attempt to slow the truck down and get into first gear. It would work for holding speed with a load or what have you of course. Once you get into first gear though it stays in first and won't upshift.... just bounces off the rev limiter. I played with mine today and that's what you get.

TX.45 · September 25, 2017

Be careful not to accidentally select M or 1, I almost had a run in with an 18 wheeler when exiting a gas station onto a rural road where speed limit was 65 or so. Truck hit rev limiter and I didn't realize I was in M and it was holding gear. I thank the 18 wheeler driver that safely got around me every day for paying attention when I did not.

redwngr · September 26, 2017

What truck do you have? Mine shows what gear it's currently in when I select manual

Yours should show the max gear available when it is in manual.

If your in manual mode and you select L4 (or if you switch to Manual mode and it goes to L4) it will continue to show L4 when you are stopped, and it will show L4 as it switches gears when sped back up.

What you have selected is the maximum gear currently available (4).

The gear it switches to when you go from D to Manual mode, depends on what gear it is in at the time of the shift.

With a 6 speed, if it is in 5 or 6, it will go to L4. If in 4th, it will go to L3. If in 3 or 2, it will go to L2.

8lugCT · September 26, 2017

Yours should show the max gear available when it is in manual.

If your in manual mode and you select L4 (or if you switch to Manual mode and it goes to L4) it will continue to show L4 when you are stopped, and it will show L4 as it switches gears when sped back up.

What you have selected is the maximum gear currently available (4).

The gear it switches to when you go from D to Manual mode, depends on what gear it is in at the time of the shift.

With a 6 speed, if it is in 5 or 6, it will go to L4. If in 4th, it will go to L3. If in 3 or 2, it will go to L2.

I have an HD. Just realized you may be talking about half tons. Mine doesn't say PRNDL 1. It says PRNDM 1. As I hit the + or - button the gear changes to what gear I'm in, and definitely does not stay in 4 when I'm stopped. I can take a video

SierraHD17 · September 26, 2017

I have an HD. Just realized you may be talking about half tons. Mine doesn't say PRNDL 1. It says PRNDM 1. As I hit the + or - button the gear changes to what gear I'm in, and definitely does not stay in 4 when I'm stopped. I can take a video

No... it just shows max selected gear.... try it. Put it in M4 and come to a complete stop without touching the buttons. It will still say M4 and the transmission will upshift and downshift up to 4th gear which it will not go beyond. When you select a gear in M it doesn't mean the trans is in that gear... most if not all replying here own an HD truck lol.

8lugCT · September 26, 2017

No... it just shows max selected gear.... try it. Put it in M4 and come to a complete stop without touching the buttons. It will still say M4 and the transmission will upshift and downshift up to 4th gear which it will not go beyond. When you select a gear in M it doesn't mean the trans is in that gear... most if not all replying here own an HD truck lol.

Hmm. I'll try it. I've played with it before though and it does change if I hit the buttons. Not entirely sure about max selected gear, but I thought the topic was about it not showing what gear you're in.

SierraHD17 · September 26, 2017

It is about not showing the gear and it doesn't. If you select M4 the truck can be in any gear from 1st to 4th and do whatever it wants... it just can't upshift beyond 4th. If you pull the truck into manual let's say at cruise on the highway it automatically goes to 4th and displays M4.. but like I said.. come to a stop and leave the buttons alone. The trans will downshift into 1st and it will still say M4.. hence not displaying what gear you are in. Or select M5 on the highway on the highway and then floor it around 60 mph.. will still downshift to 4th or 3rd... and the display still says M5.. just won't shift beyond that gear.

8lugCT · September 26, 2017

It is about not showing the gear and it doesn't. If you select M4 the truck can be in any gear from 1st to 4th and do whatever it wants... it just can't upshift beyond 4th. If you pull the truck into manual let's say at cruise on the highway it automatically goes to 4th and displays M4.. but like I said.. come to a stop and leave the buttons alone. The trans will downshift into 1st and it will still say M4.. hence not displaying what gear you are in. Or select M5 on the highway on the highway and then floor it around 60 mph.. will still downshift to 4th or 3rd... and the display still says M5.. just won't shift beyond that gear.

Well I may have misunderstood that. For that I apologize. You are right that if I switch to manual and leave it alone until I stop, it will remain on that number and will upshift until it gets to that gear. However, I can upshift from that point (or at any point) to a higher gear at any time. I'm not limited to that gear by any means. I just tested it out and have a video of me at 60mph switching from D to M and it dropped to M4. I'm then able to switch from M4 to M5 to M6 and then back down to any gear that I want, and it shifts accordingly. Am I still misunderstanding something?

sdeeter19555 · September 26, 2017

Yours should show the max gear available when it is in manual.

If your in manual mode and you select L4 (or if you switch to Manual mode and it goes to L4) it will continue to show L4 when you are stopped, and it will show L4 as it switches gears when sped back up.

What you have selected is the maximum gear currently available (4).

The gear it switches to when you go from D to Manual mode, depends on what gear it is in at the time of the shift.

With a 6 speed, if it is in 5 or 6, it will go to L4. If in 4th, it will go to L3. If in 3 or 2, it will go to L2.

Not on my 6spd...

Shifting to manual doesn't cause the trans to change gears...it simply uses that current gear as the highest gear allowed.

Sent from my SAMSUNG-SM-G900A using Tapatalk

8lugCT · September 26, 2017

Not on my 6spd...

Shifting to manual doesn't cause the trans to change gears...it simply uses that current gear as the highest gear allowed.

Sent from my SAMSUNG-SM-G900A using Tapatalk

lol wtf why is everyones different. Mine downshifts, but allows me to go to a higher gear if desired. i'll post a video of this

SierraHD17 · September 26, 2017

lol wtf why is everyones different. Mine downshifts, but allows me to go to a higher gear if desired. i'll post a video of this

Yours works like everyone else's. . Including that other guy. Of course you can select what gear you want.. if you are cruising at 70 mph and shift to M it will drop to 4th.. so click + twice and you are in 6th again and it will shift to that lol. But in M6 it operates like a normal trans and will shift through all 6 gears doing whatever it wants. Say you have M6 selected pulling a load... it won't stay in 6th and will downshift to whatever it wants like in D.

Look... everyone's works exactly the same way, but people can't understand what the hell the other is talking about. I'm done explaining lol..

8lugCT · September 26, 2017

No... everyone's works exactly the same way but people can't understand what the hell the other is talking about. I'm done explaining lol.. its pointless

lol i got what you're saying. I misinterpreted what you first said about limiting the gear to the number selected, for not being able to shift past that gear. now that i reread the whole thing, i see that you're just talking about the scenario of what that number is meaning. I originally thought you meant that it was impossible to shift past it even if you hit the + button

redwngr · September 26, 2017

Yours works like everyone else's. . Including that other guy. Of course you can select what gear you want.. if you are cruising at 70 mph and shift to M it will drop to 4th.. so click + twice and you are in 6th again and it will shift to that lol. But in M6 it operates like a normal trans and will shift through all 6 gears doing whatever it wants. Say you have M6 selected pulling a load... it won't stay in 6th and will downshift to whatever it wants like in D.

Look... everyone's works exactly the same way, but people can't understand what the hell the other is talking about. I'm done explaining lol..

Thanks for the help....!