2024 Duramax issues?

NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,516
590
113
At Da Beach
If that kit really works I’ll buy one, I’ll look into them more deeply. I know suncoast has a complete valve body as well. Wonder if it’s any good?
 

jlawles2

Well-known member
Jan 28, 2010
1,119
64
48
Danbury, TX
Im surprised they are looking at that voltage issue. Gm started using a different voltage strategy much like honda does a long while back on the gassers (not sure when they started this on diesels) but voltage will fluctuate from 12.5-15 depending on demand. Its another way to try to keep batteries alive longer and better mpg. Pretty sure my 2020 does it, never given it a second thought but ive had people bring me their gassers saying something is wrong with the voltage just like described and it’s operating as intended
Problem is the voltage is not following the charging profiles. I've had sustained voltages at 12.3 for extended periods. Really odd is truck for the first 363 days ran 13.6-13.8 on trips between Houston and Dallas or other locations. On Day 364 on the way to Florida it dropped to 12.8. Following Nephew back to Texas mine ran 12.8 (now it's down to 12.5) while his ran 13.6. His truck is a 2023 vs mine being a 2024 both L5P platforms and by all documentation I have access to they follow the same charging strategy.

Dealerships and GM have their technicians programmed that if it's not throwing a computer code there is nothing to be fixed (probably changes the instant warranty runs out).
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
16,914
3,418
113
Mid Michigan
Im surprised they are looking at that voltage issue. Gm started using a different voltage strategy much like honda does a long while back on the gassers (not sure when they started this on diesels) but voltage will fluctuate from 12.5-15 depending on demand. Its another way to try to keep batteries alive longer and better mpg. Pretty sure my 2020 does it, never given it a second thought but ive had people bring me their gassers saying something is wrong with the voltage just like described and it’s operating as intended
My 2014 Regal had this. Im pretty sure the 2016 Colorado does, too. Its unsettling to see voltage that low. Makes one think the alternator is going bad.
 

Hoser

Active member
Jun 19, 2016
243
36
28
Farmington, MN
Problem is the voltage is not following the charging profiles. I've had sustained voltages at 12.3 for extended periods. Really odd is truck for the first 363 days ran 13.6-13.8 on trips between Houston and Dallas or other locations. On Day 364 on the way to Florida it dropped to 12.8. Following Nephew back to Texas mine ran 12.8 (now it's down to 12.5) while his ran 13.6. His truck is a 2023 vs mine being a 2024 both L5P platforms and by all documentation I have access to they follow the same charging strategy.

Dealerships and GM have their technicians programmed that if it's not throwing a computer code there is nothing to be fixed (probably changes the instant warranty runs out).
The electrical architecture between your nephews truck and yours is completely different. Not positive that it changes the dynamics of the charging system, but I would bet it does.
 

skintback

Take this one to church
Mar 5, 2007
926
4
18
Florida
I bought a GMC AT4 Storm Gray 2500 crew cab short bed 4x4 back in May 2024. I like the truck its really nice and has densest power for stock but the speed limiter could be a lot higher lol it now has 15.5k on it now but the other day it died while driving down the road at 70mph. I had a brand new spare fuel pump drive module in the toolbox given the history of them failing but it would not work on the side of the road for me. But after sitting over night it worked without needing a scan tool to manually turn it on. Yes mine will sometimes charge really well and other times not so. I do not pay it that much mind as long as the lights and batteries seem good. The dealership did a few updates when it was in for the failed FPDM and i noticed a decease in mpg but the power still seems to be there. It does not use much DEF at all compared to the newer 6.7 Fords which is a plus imo

I have been looking at valve body and pump kits of all kinds. The full NextGen setup looks pretty good but they do not mention anything about increasing main line pressure in the pump in there DIY kits. I believe they sale a complete pump and valve body setup that does increase main line pressure. I'm not sure if the 10 speed RatioTek kit does anything to the pump for more pressure like there earlier kits do. I know Suncoast will sale a modified pump and complete valve body that increases main line pressure. I think they all do away with the thermostat so full time cooler flow is achieved. I believe a TCM remap on the older ones 20-23 will get you another 40-50psi increase something like that. I'm sure there is a point where you can not add to much pressure to the stock torque converter

My biggest concern is the EGR gumming things up. I wonder if you could make/install a plate somewhere in the system to restrict some of it and it not geek out. I know it monitors flow and temperature so probably not

As for stealing them I'm pretty sure they have to pickup the key fob signal so the ignition can be fully turned on so the new fob can be programed. If a new fob is not wanted you get one time to start it and take it straight to the chop shop. Company's sale a box and little bags to put your key fobs in that blocks the ability from them picking up the signal to steal it. I have one and it works
 
Last edited:

jlawles2

Well-known member
Jan 28, 2010
1,119
64
48
Danbury, TX
The electrical architecture between your nephews truck and yours is completely different. Not positive that it changes the dynamics of the charging system, but I would bet it does.
According to what I find, the charging parameters should be the same as to when it kicks in charge mode, startup mode, headlight mode, etc. Mine never enters Startup mode for starters, and charge mode is hit or miss.
 

jlawles2

Well-known member
Jan 28, 2010
1,119
64
48
Danbury, TX
I bought a GMC AT4 Storm Gray 2500 crew cab short bed 4x4 back in May 2024. I like the truck its really nice and has densest power for stock but the speed limiter could be a lot higher lol it now has 15.5k on it now but the other day it died while driving down the road at 70mph. I had a brand new spare fuel pump drive module in the toolbox given the history of them failing but it would not work on the side of the road for me. But after sitting over night it worked without needing a scan tool to manually turn it on. Yes mine will sometimes charge really well and other times not so. I do not pay it that much mind as long as the lights and batteries seem good. The dealership did a few updates when it was in for the failed FPDM and i noticed a decease in mpg but the power still seems to be there. It does not use much DEF at all compared to the newer 6.7 Fords which is a plus imo

I have been looking at valve body and pump kits of all kinds. The full NextGen setup looks pretty good but they do not mention anything about increasing main line pressure in the pump in there DIY kits. I believe they sale a complete pump and valve body setup that does increase main line pressure. I'm not sure if the 10 speed RatioTek kit does anything to the pump for more pressure like there earlier kits do. I know Suncoast will sale a modified pump and complete valve body that increases main line pressure. I think they all do away with the thermostat so full time cooler flow is achieved. I believe a TCM remap on the older ones 20-23 will get you another 40-50psi increase something like that. I'm sure there is a point where you can not add to much pressure to the stock torque converter

My biggest concern is the EGR gumming things up. I wonder if you could make/install a plate somewhere in the system to restrict some of it and it not geek out. I know it monitors flow and temperature so probably not

As for stealing them I'm pretty sure they have to pickup the key fob signal so the ignition can be fully turned on so the new fob can be programed. If a new fob is not wanted you get one time to start it and take it straight to the chop shop. Company's sale a box and little bags to put your key fobs in that blocks the ability from them picking up the signal to steal it. I have one and it works
There is a electronic gizmo out there that once the access the gm data bus, they can reprogram a new key without the old one.
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,862
966
113
Texas!!!
My biggest concern is the EGR gumming things up. I wonder if you could make/install a plate somewhere in the system to restrict some of it and it not geek out. I know it monitors flow and temperature so probably not
FASS makes a DPF for the EGR system. I know, just what you want to add is more emissions equipment, but it actually makes a little sense. If you have to have the EGR, why not filter out the soot? What I'm not sure about is how you clean it since it doesn't have the capability to do a regen.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
16,914
3,418
113
Mid Michigan
Probably set up like an oil catch can for pcv system. Periodically you've got to take the cannister off and empty it. Might even have a filter to replace. About time someone came up with an idea like that.
 

Cougar281

Well-known member
Sep 11, 2006
1,962
384
83
St Louis, MO
Probably set up like an oil catch can for pcv system. Periodically you've got to take the cannister off and empty it. Might even have a filter to replace. About time someone came up with an idea like that.
VW had an EGR filter on their TDI 15 years ago, and it was 'quite problematic'... Hopefully the fass filter is better.
 

Pure Diesel

Well-known member
Apr 22, 2008
986
296
63
Ventura County
Well I've got bad news. After two weeks the dealer calls and says they have the a new valve body for my truck. I tell them that unless its a totally new one and a different part number that this isn't going to work and is just a band aid. I tell the service manager about Next gen and the parts they have and he says that they can't use their parts. I told him to contact the area supervisor and to relay the info. He calls back and gives me the number to GM engagement specialists and I talked to them. About two days go by and they call back and say that GM will not authorize any third party parts for the repair. So basically I now have to have the truck repaired by GM if I want to keep my factory warranty intact or I can have an outside repair shop do it with the Next Gen parts and be out of warranty.
I talked with two guys from Next Gen and they said that they had dealerships buying their parts and repairing the trucks. They never said whether it was going to be under warranty or not. I think owners were just saying screw it and just fix the truck or Next Gen was blowing smoke to get you to just buy their stuff. Since I passed on the repairs the first time, I now have to wait for them to order parts for mine and wait again. Funny thing was the service manager said he had 3 other trucks waiting to be repaired. I was talking to a friend in Central CA, who has a 2021 truck, and he has two friends with 2022 and a 2024 waiting for the same repair. This issue is going to turn into huge lawsuit for GM.
 

skintback

Take this one to church
Mar 5, 2007
926
4
18
Florida
The ignition has to be fully turned on to access the data bus on the truck otherwise I do not see how they can program a new fob with the truck turned off? I'm sure the vin number is needed as well. Maybe stick something over that in the windshield to delay things LOL

The only way I see that happening is with the original fob being close enough to the truck or by picking up the fobs signal from a special antenna that is sold online and anybody can buy one probably hooked up to a laptop with the needed software and knowledge then a new fob can be programed and then they drive off with the truck?


As for having Valve body issues 2020-25 modules if you don't feel confident enough installing the complete 'Fix' Next Gen valve body kit they sale looks like you can send them your old valve body and they will 'fix' it and stand behind it
 
Last edited:

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
23,033
8,045
113
Phoenix Az
As for having Valve body issues 2020-25 modules if you don't feel confident enough installing the complete 'Fix' Next Gen valve body kit they sale looks like you can send them your old valve body and they will 'fix' it and stand behind it

I think his concern is more if an issue happens with the trans and the aftermarket stuff is inside, they wont warranty it
 

LBZ

Super Moderator
Staff member
Jul 2, 2007
9,963
236
63
47
B.C.
I think you guys need to get back in an obs or a classic for a bit to remember what comfortable seats really feel like lol!

Hated the hard uncomfortable seat in my ‘20 AT4. My ‘23 Sierra 3500 work truck is ridiculous hard. My ‘16 I felt was better but not much. I’m pretty sure angels designed the classic seats!

All the reading I’ve done in this thread really makes me appreciate my decision to go back to the OG DMAX. On that note however, my buddy hasn’t had any issues yet with his ‘24 Denali. Nor has my neigbor with his ’24 AT4 gasser. I do like the 10 speed in my ‘23 though. Might have kept my AT4 if had it.

My gm dealer diesel tech buddy hasn’t seen lots of trans issues in the 10 speed. Not much electrical yet.