Auto Grade Braking & Exhaust Brake Inop.

[JRSPerf.]

Hello everyone! I am a new member here and just looking for some clarification if anyone can help. I have a 2020 Silverado 3500HD HC Duramax DRW, 7kmi. My vehicle also suffers from almost every topic in this forum from day 1! From the low thud from engine at idle, steering column/intermediate shaft/ steering box noise, vibration at hw speed, pulling/steering wheel to the right, infotainment cutting out screen blank no audio, transmission bell housing leak, to it sounding like a freight train every time I would come to a stop!! It is so frustrating that a brand new vehicle would have so many issues!! I absolutely love this truck but cannot do the back and forth with the service dept.!! I took it in to address the concerns I had after spending some time driving around. I wrote a detailed list explaining all the concerns and how they could be replicated (night time drop off). I did not receive a phone call from the service department for (4) days, each day my vehicle was in I would try to contact my service advisor but would only get her answering machine, many messages left with no return call! Finally on day (4) she leaves a message that my vehicle was done and may be picked up. I called her back immediately but again only got her machine. I go in to pick up my vehicle and my advisor convientaly left for the day. I spoke to another advisor and went over what was done to address the concerns I had. Most of what I had listed out on my original concern list never even made it to the RO!! They advisor explained that basically there were a few updates performed, programming for the steering control module(vibration issue), reductant module update, radio software update, engine control module programming, road force balance front wheels, retorqued the rear leaf spring brackets & they had to order the front and rear brakes pads. When I asked about the low thud from the engine he said it was normal and would not cause any harm to the long term durability of the engine. When I asked about the rattle/knocking noise from the steering column he said that the steering control module update should also take care of that, I thought that was weird but got in my truck and drove away. Absolutely NONE of the concerns I have are repaired, every single concern is still there!! Also now and this is where I am seeking clarification I noticed that the auto grade braking feature(I absolutely loved) and the Exhaust brake no longer work or at least are not working they way they use too!! Does anyone have this issue after vehicle programming? I am convinced that when the vehicle was programmed to address the other concerns that it either inadvertently programmed out these features or at least changed the drive logic behind how these features operate. I have a long steep hill that I travel down everyday and when coming down this hill (in NORMAL drive mode) originally I would just have to tap my brakes and the trans. would dwn shift as the rpms would jump to 2500/2800 and I would not have to use my brakes again coming dwn this hill as the auto grade braking was doing its job! Now it doesn't even dwn shift, nothing, I have to ride the brakes all the way down the hill. I have a fith wheel toy hauler that I tow with it and yes I followed all the break in periods before towing with the new truck, before the exhaust brake did an amazing job and came in strong to slow the beast down now it doesn't even come on even thought the system is on! I have no fault display messages no fault codes so the dealer tells me everything is working fine. I know for a fact that every thing is definitely not working fine but no fault codes so no problem as far as the service department is concerned! Does anyone have this issue!? Does anyone know if the parameters may have been changed for these systems with new software release as when I research these features I find a ton of people complaining about how aggressive they are especially the auto grade brake and want to turn it off. Sorry this has been a long read if you made it to this point but I am desperate to figure this out. 

[kylant]

i would have a tough time believing having the updates you had done would affect the exhaust brake or grade braking. I don't think those could be programmed out

 

good luck

[Tomato]

3 hours ago, JRSPerf. said:

Hello everyone! I am a new member here and just looking for some clarification if anyone can help. I have a 2020 Silverado 3500HD HC Duramax DRW, 7kmi. My vehicle also suffers from almost every topic in this forum from day 1! From the low thud from engine at idle, steering column/intermediate shaft/ steering box noise, vibration at hw speed, pulling/steering wheel to the right, infotainment cutting out screen blank no audio, transmission bell housing leak, to it sounding like a freight train every time I would come to a stop!! It is so frustrating that a brand new vehicle would have so many issues!! I absolutely love this truck but cannot do the back and forth with the service dept.!! I took it in to address the concerns I had after spending some time driving around. I wrote a detailed list explaining all the concerns and how they could be replicated (night time drop off). I did not receive a phone call from the service department for (4) days, each day my vehicle was in I would try to contact my service advisor but would only get her answering machine, many messages left with no return call! Finally on day (4) she leaves a message that my vehicle was done and may be picked up. I called her back immediately but again only got her machine. I go in to pick up my vehicle and my advisor convientaly left for the day. I spoke to another advisor and went over what was done to address the concerns I had. Most of what I had listed out on my original concern list never even made it to the RO!! They advisor explained that basically there were a few updates performed, programming for the steering control module(vibration issue), reductant module update, radio software update, engine control module programming, road force balance front wheels, retorqued the rear leaf spring brackets & they had to order the front and rear brakes pads. When I asked about the low thud from the engine he said it was normal and would not cause any harm to the long term durability of the engine. When I asked about the rattle/knocking noise from the steering column he said that the steering control module update should also take care of that, I thought that was weird but got in my truck and drove away. Absolutely NONE of the concerns I have are repaired, every single concern is still there!! Also now and this is where I am seeking clarification I noticed that the auto grade braking feature(I absolutely loved) and the Exhaust brake no longer work or at least are not working they way they use too!! Does anyone have this issue after vehicle programming? I am convinced that when the vehicle was programmed to address the other concerns that it either inadvertently programmed out these features or at least changed the drive logic behind how these features operate. I have a long steep hill that I travel down everyday and when coming down this hill (in NORMAL drive mode) originally I would just have to tap my brakes and the trans. would dwn shift as the rpms would jump to 2500/2800 and I would not have to use my brakes again coming dwn this hill as the auto grade braking was doing its job! Now it doesn't even dwn shift, nothing, I have to ride the brakes all the way down the hill. I have a fith wheel toy hauler that I tow with it and yes I followed all the break in periods before towing with the new truck, before the exhaust brake did an amazing job and came in strong to slow the beast down now it doesn't even come on even thought the system is on! I have no fault display messages no fault codes so the dealer tells me everything is working fine. I know for a fact that every thing is definitely not working fine but no fault codes so no problem as far as the service department is concerned! Does anyone have this issue!? Does anyone know if the parameters may have been changed for these systems with new software release as when I research these features I find a ton of people complaining about how aggressive they are especially the auto grade brake and want to turn it off. Sorry this has been a long read if you made it to this point but I am desperate to figure this out. 

What is your build month and year from the door sticker?

[JRSPerf.]

01/20

[Tomato]

1 hour ago, JRSPerf. said:

01/20

Dang. Same build date as my DRW.  I have the thump, of course, and had the steering issue.  An alignment was ultimately the fix for the steering shake.  Only problem I am dealing with now is "gremlins" with the trailering app - mileage tracking and TTPMS "disconnecting."

[GLW]

Don't have many issues, but I have had it to the dealer for the engine brake.  I don't care what they say, the engine brake doesn't work!  I cannot tell the difference in tow/haul or standard.  The engine brake should slow the vehicle, isn't that why it's called a BRAKE!  Looking for any recall or info anyone may have.  My GM service tech. said there is a bulletin on the engine brake issue, but cannot find anything.

[JRSPerf.]

Gm did have a bulletin on the exhaust brake at one time but it has since disappeared. GM replaced it with what my Service dept. handed me, a GM document stating some customers may have concerns with the exhaust brake operations and how it may feel like it isn't working. It states that if the button is pressed (exhaust brake button) and the message "exhaust brake on" is displayed in the cluster the system is operational, they stand by the fact that this is the way it has been designed to operate for a "better driving experience". No explanation on why the "auto grade brake" is no longer working. They can not however discount the fact that I have had my vehicle for 6 months, drove over 5k miles and my vehicle operated in a very specific way when it came to the auto grade brake and the exhaust braking! I am not concerned with how I believe it should work nor am I concerned with the fact that it doesn't "feel" like it is working. I am not comparing it to how another vehicle feels, I am concern with the fact that MY VEHICLE use to do something a particular way for 6mnths and 5k miles. It no longer does what it use to do and the only thing that happened in between was a service dept. Visit where the vehicle was programmed! There must be a split somewhere in production where the earlier production vehicles software allowed the system to operate the way mine use to, the way It should operate, in a later production vehicle this system seems to be detuned and feels like its not there at all. If you search this issue anywhere there is a very dramatic split where some people are complaining about how aggressive it is and hate the fact that it can not be turned off(auto grade braking) like in the older models (2013-19). Then there is the later production vehicles that feel like this feature isn't even there and is supported by the GM document. This would also explain why my early production vehicle that was programmed with the latest software now operates completely different! Software changes the way vehicles operate this is why they are programmed/updated!! So the fact that someone can say to me that "they would have a tough time believing" that software could inadvertently be the cause of my issue has no clue what they are talking about and should not comment!! 

[newdude]

1 hour ago, JRSPerf. said:

Gm did have a bulletin on the exhaust brake at one time but it has since disappeared. GM replaced it with what my Service dept. handed me, a GM document stating some customers may have concerns with the exhaust brake operations and how it may feel like it isn't working. It states that if the button is pressed (exhaust brake button) and the message "exhaust brake on" is displayed in the cluster the system is operational, they stand by the fact that this is the way it has been designed to operate for a "better driving experience". No explanation on why the "auto grade brake" is no longer working. They can not however discount the fact that I have had my vehicle for 6 months, drove over 5k miles and my vehicle operated in a very specific way when it came to the auto grade brake and the exhaust braking! I am not concerned with how I believe it should work nor am I concerned with the fact that it doesn't "feel" like it is working. I am not comparing it to how another vehicle feels, I am concern with the fact that MY VEHICLE use to do something a particular way for 6mnths and 5k miles. It no longer does what it use to do and the only thing that happened in between was a service dept. Visit where the vehicle was programmed! There must be a split somewhere in production where the earlier production vehicles software allowed the system to operate the way mine use to, the way It should operate, in a later production vehicle this system seems to be detuned and feels like its not there at all. If you search this issue anywhere there is a very dramatic split where some people are complaining about how aggressive it is and hate the fact that it can not be turned off(auto grade braking) like in the older models (2013-19). Then there is the later production vehicles that feel like this feature isn't even there and is supported by the GM document. This would also explain why my early production vehicle that was programmed with the latest software now operates completely different! Software changes the way vehicles operate this is why they are programmed/updated!! So the fact that someone can say to me that "they would have a tough time believing" that software could inadvertently be the cause of my issue has no clue what they are talking about and should not comment!! 

 

 

I assume this is the document they gave you for the exhaust brake?

 

 

Quote

 

#PIP5735: Exhaust Brake Feel - (Jun 16, 2020)

Subject:

Exhaust Brake Feel

---

Brand:	Model:	Model Year:		VIN:		Engine:	Transmission:
		from	to	from	to
Chevrolet	Silverado	2020		All	All	6.6 L5P	All
GMC	Sierra	2020		All	All	6.6 L5P	All

 

Involved Region or Country	North America
Condition	A customer may complain that the exhaust brake does not seem to work.
Cause	The technician may find that there are no codes set or messages on the DIC.

Correction

The information below may be useful when addressing a vehicle with this complaint:

There were many improvements with the new Allison transmission in the 2020 Duramax. Some of the changes have to do with the feel of the exhaust brake.  Prior to 2020 model year, the movement of the turbocharger vanes was very rapid so that a customer could feel the engagement of the exhaust brake. In model year 2020, the movement of the vanes is slower. This can give the feel that the exhaust brake is not functioning properly.  As long as the customer sees the message that states EXHAUST BRAKE ON and there are no codes set, the vehicle is functioning properly.

The following is from the owner’s manual describing the exhaust brake operation:

Automatic downshifts will not occur if the vehicle is in Range Selection Mode. See “Manual Mode” in the owner’s manual. The exhaust brake only activates when the transmission torque converter is locked. This can vary based on vehicle speed, gear, and load. To activate the system, press the EXHAUST BRAKE button on the center stack. A light in the switch will come on when the exhaust brake is activated. The switch must be pressed at each vehicle start for the system to be active. The Driver Information Center (DIC) displays the message EXHAUST BRAKE ON for approximately three seconds, then clears. To turn the brake off, press the exhaust brake switch a second time. The DIC displays the message EXHAUST BRAKE OFF for approximately three seconds, then clears. The exhaust brake will be more active when in Tow/Haul Mode.

 

 

 

 

Here is the one for the knock noise:

 

 

Quote

 

#PIP5711: 2020 6.6 L5P Duramax Warm Engine Idle Knock Noise - (Mar 3, 2020)

Subject:

2020 6.6 L5P Duramax Warm Engine Idle Knock Noise

---

Brand:	Model:	Model Year:		VIN:		Engine:	Transmission:
		from	to	from	to
Chevrolet	Silverado 2500/3500	2020		All	All	6.6 L5P	All
GMC	Sierra 2500/3500	2020		All	All	6.6 L5P	All

 

Involved Region or Country	North America
Condition	Customers may have a concern of a thumping or knocking noise coming from what sounds like the rear of the engine.
Cause	Characteristic noise being amplified by the transmission bell housing.

Correction

The noise described in this communication is audible in the interior and exterior of the vehicle but is more pronounced in the interior.

The noise is easiest to duplicate under the following conditions:

Engine at idle (about 600 RPM)

Engine oil temperature 113 - 185 degrees Fahrenheit (45 - 85 degrees Celsius) 

Transmission in P/N

HVAC fan off

Radio off

To verify this is the noise described in this PI, remove the accessory drive auxiliary belt.  If the noise level is significantly reduced it should be considered characteristic of the 2020 MY truck and no further repair attempts should be made.

Engineering has provided the following procedure for belt removal, testing and installation:

1. Remove the air cleaner housing.
2. Remove intake air duct.
3. Separate the charge air cooler (CAC) tube and position aside.
4. Remove belt and position aside.
5. Install CAC tube.
6. Loosely place air box and intake duct back in place. (So you don’t set a code for sensor when starting.)
7. Start engine and verify noise is gone.
8. Remove loosely installed air box and intake duct.
9. Separate CAC tube.
10. Install belt.
11. Install CAC tube.
12. Install air box and duct.

Note: Do not run the vehicle more than three minutes without the auxiliary belt installed. Do not raise the RPM higher than idle with the belt removed.

This noise has no short or long term effects on the engine. Do not attempt repairs for this noise.

 

 

[JRSPerf.]

Yes that is the document for the exhaust brake. Press the button, light comes on, no fault codes, all good as far as chevy service is concerned! They Do not take into account that it operated the exact opposite from day1 to the first service visit! Also no mention about the "auto grade brake feature". That bulletin is dated June 2020, yes I see from & to (all prod.) I'm not making something up here! The vehicle use to do something it no longer does and It stopped doing it after and only after it was programmed. Really not that hard to see the issue here!! That document is a blanket statement also clearly states that the reason why it "feels different" is "Now the turbo charger vanes move slower"! A control module controls an actuator that move the vane assembly and therefore relies on a program to control said function! Why is this so hard for GM to grasp!?!? I'm Not saying that later software developed and installed into later vehicles are not "operating as designed" in fact thats EXACTLY WHAT I'M SAYING HERE!! My vehicle doesn't do something it use to do all that changed is the software!! This is simple logic!! 

 

[firedab]

Had a 2016, exhaust brake worked wonders, barely had to use the brakes, then upgraded to 2020 and I lost the exhaust brake! I feel the switch is just a dummy switch now, does nothing to help slow the truck down, and I tow 10k pound trailer all the time, I can tell you loaded or empty is absolutely the same. Wish they would let the engine brake be an engine brake, and reprogram it to work like it used to in the older generation trucks.

[JRSPerf.]

1 hour ago, firedab said:

Had a 2016, exhaust brake worked wonders, barely had to use the brakes, then upgraded to 2020 and I lost the exhaust brake! I feel the switch is just a dummy switch now, does nothing to help slow the truck down, and I tow 10k pound trailer all the time, I can tell you loaded or empty is absolutely the same. Wish they would let the engine brake be an engine brake, and reprogram it to work like it used to in the older generation trucks.

What is the build date of your vehicle? Mine is 1/20. Before my vehicle was RECENTLY  programmed my "Auto grade brake" & also the "Exhaust brake" was much more aggressive than my 2015 duramax. I actually wasn't even aware that the 2015 had the "Auto grade brake" feature. Yes I was well aware of the "Exhaust brake" in the 15 and it worked well but never once felt the "Auto grade brake" kick in or have the message come up in the dash that this feature was active. It wasn't until 5yrs later when I purchased the 2020 that I was introduced to the "auto grade brake" in "Normal" drive mode feature, not to be confuse with the "Exhaust brake feature". The exhaust brake feature is a manually selected feature(button/switch operated) the "Auto grade brake in "Normal" drive mode is always active on every key cycle in the 2020 and cannot be turned off in the 2020 like it can in the earlier models by holding the tow/haul mode button for 3 sec. The first time I was introduced to the "auto grade brake" In the new 2020 I was coming dwn a decent grade(hill) on a road that I travel every day, I stepped on the brake pedal a little bit and immediately the truck responded by dwn shifting aggressively(feels very similar to the exhaust brake when towing) and held that until I stepped on the gas pedal at the bottom of the hill, never again did I have to step on the brake and if I did it would dwn shift again!! It continued to do this & in my opinion do it very well, on every decent hill including that one that I traveled on and applied the brakes, my absolute favorite "NEW" feature (I thought it was a new feature)on the 2020. . Also the Exhaust brake feature in tow/haul mode is no longer working. I too tow a big 5th wheel toy hauler with my truck same trailer same weight as always and the "Exhaust Brake" use to come in super aggressive(better than the 15) when it was on and I was towing up until that first service visit. Now its as if like you said "the switch is a dummy switch" it has no effect at all!! My problem is, This truck, the 2020 use to do what my 15 did but even better in my opinion because I didn't even know the 15 had the "auto grade brake" in normal drive mode!! Actually in the 2020 my wife sitting in the passenger seat notice it immediately the first time we felt the auto grade brake kick in and asked me if I had the exhaust brake on(I didn't), then she thought something was wrong with the truck because like I said our 2015 that we had bought new until we traded up for the 2020 never did The auto grade brake feature in normal drive mode atleast not to me being able to notice it! This is driving me crazy that they (chevy service) keep telling me that everything is fine when I know it use to do it differently until that visit!! I refuse to eat that crap that this is how it is designed to operate when this exact truck use to do it better!! It would be like them telling me that my drivers window never rolled down, I know it does, you know!? Same thing here, it did it now it doesn't and they tell me that it never did it!! DRIVING ME CRAZY!!!!!

 

[firedab]

So, I have recently upgraded from my 2020 Sierra Denali 2500 to a 2020 Sierra AT4 3500. My 2500 had what I felt, no difference between on or off of the exhaust brake. Either empty or towing, same nothing from the brake. I will say the descent braking is the only thing that does work. Empty or towing with exhaust brake switch on or off, it would always downshift as soon as I tap the brakes while going downhill, which is what my 2015 did on level ground with exhaust switch on! My 3500 only has 350 miles on it and I have not towed with it yet. But, I can tell you the switch on or off does not make a difference so far not towing.