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Auto Grade Brake

JRSPerf.

By JRSPerf.
in 6.6L Duramax Diesel (L5P)

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JRSPerf. Enthusiast

JRSPerf.

Posted
Posted

I am reaching out to our community. If you own a model year 2020 Silverado/Sierra 2500/3500 DURAMAX Please attach a video clip of the instrument cluster while traveling down a grade(hill) and applying the brake briefly to activate the Auto grade brake feature. I am really looking for early production vehicles here but any and all that are MODEL YEAR 2020 will help, the earlier the better. This will not take long and your help will be GREATLY appreciated!! Please note the production date of your vehicle this can be found on the B-pillar placard. Also if the vehicle has been into the dealership for any service/recall/SIB that required your vehicle to programmed(updated software) please note that as well. THANK YOU!!!!!!

JRSPerf. Enthusiast

JRSPerf.

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49 minutes ago, davester said:

what are you using this information for?

Hello davester. I have a 2020 silverado 3500 hc drw, My build date is 01/20. Long story short my vehicle's auto grade brake function no longer works or at least not operating the way it use to before I had it in for service. Before the service visit I had my vehicle for 6mnths and drove 5kmi. and every time I would go down a decent grade hill if I tapped the brakes the auto grade brake would kick in and hold a higher rpm all the way down until I pressed the gas pedal to accelerate again. After the service visit it no longer does this, at all, it doesn't even drop a gear! It has now lived at the dealership for 47 days bc they can not find anything wrong with it. I believe that when it was in for service and had to be programmed something was inadvertently changed. I just need a video of someone's vehicle who's Auto grade brake in "Normal" drive mode is actually doing what it is suppose to do! This is a weird issue because only the early version/builds operated this way, newer builds with the newer software operate as if its not even there. It drives me nuts because I loved that feature about this truck!! If you could help me out I would be so grateful, thank you my friend.

JRSPerf. Enthusiast

JRSPerf.

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Soooo, not one person on here owns a 2020 duramax and is willing to attach a 10sec. Video clip to help out a fellow member!? Over 100 views on this post and almost 500 on another just like it but not one video!! All I need is a short video to show the service dept. the way it should be operating!! They have nothing there to compare it to. This is something big here and can also help you out in the long run bc I'm telling you if you take your truck in for service and it gets programming you will now be in the same situation I am in now!!! This is to convince GM to take a look into their software to make changes! They are using my truck basically now as  test truck to figure this out! GM Engineering is involved but all they have to look to are new trucks with the updated software. 

LSPowered65 Enthusiast

LSPowered65

Posted
Posted

Mine was built 12/19. It doesn’t do that.  My grade braking doesn’t come on in normal driving unless I’m really on the brakes. In tow haul it activates much quicker. Maybe you aren’t getting a response because others aren’t having the same issues as you. 

JRSPerf. Enthusiast

JRSPerf.

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Posted (edited)
6 hours ago, LSPowered65 said:

Mine was built 12/19. It doesn’t do that.  My grade braking doesn’t come on in normal driving unless I’m really on the brakes. In tow haul it activates much quicker. Maybe you aren’t getting a response because others aren’t having the same issues as you. 

That qualifies as a response though! I am not the only one who's vehicle operated this way, check out the post by JHARRIS32 "HIGH RPMs downhill". Has your vehicle been to the service dept.? Any programming, maybe for the "Reductant control module SIB"? 

Edited by JRSPerf.
JRSPerf. Enthusiast

JRSPerf.

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LSPowered65 A friend of mine had an AT4 3500 Build date 08/19 and his did it as well(he no longer owns that vehicle), Maybe bc yours is a 2500!? Not sure but all I know is I have over 20Yrs in the automotive service industry, Dealership Certified Master Technician. I know the way it use to operate and how it does now. Software is the issue. This is why I put this out there, feedback from different members, build dates, 2500 or 3500, all this helps and that is all I am looking for. 

LSPowered65 Enthusiast

LSPowered65

Posted
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The day I drove mine off the lot it threw a code for a sensor in the exhaust, it was replaced 2 days later. This was late February. It has always driven the same way in regards to its downshifting for speed control. It will do it in normal mode if i am repeatedly on the brakes. Happens much quicker in tow haul. 

JRSPerf. Enthusiast

JRSPerf.

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13 minutes ago, LSPowered65 said:

The day I drove mine off the lot it threw a code for a sensor in the exhaust, it was replaced 2 days later. This was late February. It has always driven the same way in regards to its downshifting for speed control. It will do it in normal mode if i am repeatedly on the brakes. Happens much quicker in tow haul. 

Thank you for the info. I really do appreciate the feedback. It is almost certain that your vehicle was also programmed at that time. I understand what you are saying when you say that yours has operated the same way since day one if that is the case. This is a problem with current level software, not sure of the exact change time frame but that is what we are trying to figure out, also to that point ALL newer vehicle would perform as such(same as yours). Mine was very distinctive in it's operation, light brake application down a grade(hill) in NORMAL drive mode WITHOUT the Exhaust Brake Turned on it would very noticeably down shift and hold a higher RPM until I stepped on the gas pedal to accelerate.  

CAMPINGCPL Enthusiast

CAMPINGCPL

Posted
Posted

I just had mine reprogrammed for DEF. my exhaust brake doesn't seem to come on at all now when not towing and I definitely notice the lack of auto grade braking. Will investigate further. 

JRSPerf. Enthusiast

JRSPerf.

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On 11/22/2020 at 10:08 PM, CAMPINGCPL said:

I just had mine reprogrammed for DEF. my exhaust brake doesn't seem to come on at all now when not towing and I definitely notice the lack of auto grade braking. Will investigate further. 

Thank you for the feedback, please keep me updated if you get somewhere.

shadow gray 2020 hd Enthusiast

shadow gray 2020 hd

Posted
Posted

Build date on my truck is 8/20.  I don't get into the mountains or anywhere where there are steep enough grades to notice.  With just over 2000 miles on it have not even turned the auto grade braking on yet.  If in the event I do drive somewhere that has a grade and I use the brakes like you post, I will try to remember to take a short video.  

JRSPerf. Enthusiast

JRSPerf.

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10 hours ago, shadow gray 2020 hd said:

Build date on my truck is 8/20.  I don't get into the mountains or anywhere where there are steep enough grades to notice.  With just over 2000 miles on it have not even turned the auto grade braking on yet.  If in the event I do drive somewhere that has a grade and I use the brakes like you post, I will try to remember to take a short video.  

Thank you my friend for the info. The Auto Grade brake feature NOT to be confused with the Exhaust Brake Feature are (2) seperate features. The Auto Grade Brake is ALWAYS active and cannot be turned off like in previous models, I believe the only way for it to not operate is with the vehicle in the Manual Shift Mode. The Exhaust Brake is Turned on/off via a switch and is mainly utilized in tow haul mode. My vehicle being an earlier build date (01/20) was super aggressive when both of these features were active, after it went in for a service visit it received a software update for the DEF(reductant fluid) module SIB and whatever else they had to program which in my opinion completely rendered the Auto Grade brake and the Exhaust brake features basically inoperable. It would now make sense as to why so many people complaining that their Exhaust Brakes don't or do not feel like it is working in their 2020. My vehicle's Auto Grade Brake and Exhaust Brake were AMAZING until that new software. After a certain production date that new software was implemented in the assembly so vehicle's are rolling out to the dealerships that way. My goal was to gather up as many people with early build dates and who's braking features STILL worked the way mine originally did before the update to take back to my service dept. So they can forward the issue to GM. My service dept. has no idea what I am talking about because everything they have to compare has the NEW software version and the inadequate braking features. Really sad that no one will ever get to enjoy the way these systems are suppose to work!!

shadow gray 2020 hd Enthusiast

shadow gray 2020 hd

Posted
Posted
15 hours ago, JRSPerf. said:

The Auto Grade brake feature NOT to be confused with the Exhaust Brake Feature are (2) seperate features. The Auto Grade Brake is ALWAYS active and cannot be turned off like in previous models, I believe the only way for it to not operate is with the vehicle in the Manual Shift Mode. The Exhaust Brake is Turned on/off via a switch and is mainly utilized in tow haul mode.

Ok.  I know the exhaust brake has a switch/button, but thought you were talking about the button on the right side of the row of buttons that has the symbol of the truck going down hill.  Have never used that button.  

 

fwiw, my truck does seem to downshift going downhill after pushing the brakes to come off cruise.  But has not been in any way aggressive.  I will pay closer attention.  

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