Jump to content

SERVICE BRAKE ASSIST / 2020 SIERRA

Denali2020
 Share

Recommended Posts

Denali2020 Enthusiast

Denali2020

Posted
Posted (edited)

Hey all! I just got a brand new 2020 Denali off the showroom floor . It has a message in the dash  “service brake assist”. It was even on while I took it for a test drive. Long story short Looks like the dealer is replacing the master cylinder. Not sure what the full scope of the techs report is yet, I’ll keep everyone posted. My vin has no recall in the NHTSA,  but that can always change.. 

87CF493B-2C8C-4662-BE6D-F82CF576CD3D.jpeg

Edited by Denali2020
mis spelled the Sierra
steve841 Enthusiast

steve841

Posted
Posted (edited)

Amazing they still cant get it right ...  the brake system on the 19s was a total foul up of software and master cylinders.

Edited by steve841
Denali20 New Member

Denali20

Posted
Posted
On 4/14/2020 at 3:50 PM, Denali2020 said:

Hey all! I just got a brand new 2020 Denali off the showroom floor . It has a message in the dash  “service brake assist”. It was even on while I took it for a test drive. Long story short Looks like the dealer is replacing the master cylinder. Not sure what the full scope of the techs report is yet, I’ll keep everyone posted. My vin has no recall in the NHTSA,  but that can always change.. 

87CF493B-2C8C-4662-BE6D-F82CF576CD3D.jpeg

I have the same issue on my 2020, purchased a month ago. Just brought it in with less than 500 miles on it. They “reprogrammed all the modules” and the fault cleared. Two days later, the fault appears again every time I start it. Bringing it in again this week. What led them to replace the master cylinder? Please let us know when you find out.

Denali2020 Enthusiast

Denali2020

Posted
  • Author
Posted

Hey all! All they told me is that it was a major recall. I think they didn’t want me to be upset, after I only had the truck a week. They replaced brake master cylinder, brake module, and replaced all the brake lines. I’ll say the dealer did a great job, I couldn’t even tell they did all that work, as I also am a former Tech myself. It was Big  job especially for a brand new truck with 100 miles on it . I will say the code is gone so far, almost a week now, the code would come back hours later after they cleared it, I’m pretty confident they fixed it. Here is a copy of the report. I would absolutely keep hounding your local dealer to fix the code, it’s in for a reason, and it’s not going to go away!

2C1A0365-9E16-4255-9F11-C4A8BE18A2CA.jpeg

  • Like 1
Denali2020 Enthusiast

Denali2020

Posted
  • Author
Posted

My pleasure, I was once in the dark about this. I’m so glad I could help others with this info. Apparently the infamous brake recall they had a couple years ago has lingered into the 2020 models as well. Just be very careful driving it. I did not experience any brake lag or failure,  it only had the annoying light on. But I’ve read other posts who had the same light and had brake issues. Aside from that how do you like your truck? I love it, I refuse to let the recall stop me from enjoying it!  

newdude Senior Enthusiast

newdude

Posted
Posted
41 minutes ago, Denali2020 said:

Hey all! All they told me is that it was a major recall. I think they didn’t want me to be upset, after I only had the truck a week. They replaced brake master cylinder, brake module, and replaced all the brake lines. I’ll say the dealer did a great job, I couldn’t even tell they did all that work, as I also am a former Tech myself. It was Big  job especially for a brand new truck with 100 miles on it . I will say the code is gone so far, almost a week now, the code would come back hours later after they cleared it, I’m pretty confident they fixed it. Here is a copy of the report. I would absolutely keep hounding your local dealer to fix the code, it’s in for a reason, and it’s not going to go away!

 

 

 

Not sure as to why they would put lines in?  Something must have failed in the brake module to get the module/master assembly though.  The recall(s) are nothing more than reprograms to the brake module.  

Denali2020 Enthusiast

Denali2020

Posted
  • Author
Posted

I mis1quoted looks like he reinstalled the lines .. but I was surprised as well as to the amount of work needed from the fix. So something from the previous recalls must have been amended by GM to fix the issue, for all we know this could be a new issue itself.. 

Denali2020 Enthusiast

Denali2020

Posted
  • Author
Posted

Just wanted to update everyone. Its been almost two weeks now, and so far the "Service brake assist" Message has not returned. 

 

 

 

Andrew - 

 

 

  • Like 1
Denali20 New Member

Denali20

Posted
Posted
11 hours ago, Denali2020 said:

Just wanted to update everyone. Its been almost two weeks now, and so far the "Service brake assist" Message has not returned. 

 

 

 

Andrew - 

 

 

Thanks for the update. Mine is back at the dealer now for over a day now. I’ll update this thread when I hear what the issue/fix was.

 

I love it other than this issue that hopefully gets solved soon!

Denali2020 Enthusiast

Denali2020

Posted
  • Author
Posted

Maybe, but they did way more work than that. I attached the report from the tech in the earlier post of the chain. Keep in mind new recalls and procedures can be issued/changed/modified from the manufacturer at anytime. I believe the original fix was a software update , then that turned out to be disastrous, then there was a replacement fix for that recall...I could be wrong, just thought I read that somewhere. Thanks for the reply! 
 

 

Andrew - 

Denali20 New Member

Denali20

Posted
Posted

I got mine back from the dealer yesterday. It was generating a new code from when I had it in last week. They replaced the master cylinder, same as the notes posted above. So it appears more than just a re-flash. Hopefully it’s solved now.

Denali2020 Enthusiast

Denali2020

Posted
  • Author
Posted

Hey! 
 

well I’m glad to hear they took you seriously, and started somewhere to fix it. I’m betting you will be good to go though now! So far I still have no codes after that procedure. 

  • 2 weeks later...
Rixky New Member

Rixky

Posted
Posted

Brand new Silverado 400 miles.  All lights came on.  (Trailer brake asst, abs, check engine light) brake pedal was really hard. Truck will not pass 42 mph.  Not happy.  I used to have a Toyota truck never had a issue in 7 years.  I think this truck is a lemon.   Going to the dealer on monday.   ????

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.4k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,760
    Total Members
    8,960
    Most Online
    MASONV88888888
    Newest Member
    MASONV88888888
    Joined

  • Who's Online   2 Members, 0 Anonymous, 1,622 Guests (See full list)

  • Latest Articles

  • Posts

    • Coastie05
      Replacing 2.7L on 2021 Silverado with 2023 2.7L

      By Coastie05 · Posted

      I’m definitely interested to hear the end result here. 
    • MASONV88888888
      Another 6.2L engine failure!

      By MASONV88888888 · Posted

      My 2025 Silverado 1500 had to receive a brand-new engine (long block) under warranty last month at only around 16,500 miles. Before the replacement, the truck repeatedly displayed "Engine Oil Level Low" warnings, even though the Oil Life Monitor still showed around 50% remaining after about 6,000 miles since my last oil change. After seeing the warning several times, I checked the dipstick with the engine cold, and the oil level was completely normal. The next day, the message escalated to "Add Engine Oil." At first, I assumed it was just a faulty oil level sensor, so I brought the truck to the dealership. After inspecting the engine, they found internal cylinder wall scoring and ultimately replaced the entire long block under warranty. Before this happened, I was planning to install a 4-inch lift and suspension upgrade on my truck. After needing a new engine at just 16,500 miles, I honestly don't see the point anymore. I also contacted GM to ask whether my vehicle qualified for a buyback, but I was informed that it does not at this time. Anyway, this experience has left me with serious concerns about the long-term reliability of this engine. I sincerely hope NHTSA expands the current investigation or recall to include 2025 model and performs a thorough inspection of affected vehicles. My biggest concern is that these engines may fail shortly after the powertrain warranty expires. If GM truly stands behind this engine, then at the very least, please consider extending the powertrain warranty to 10 years for affected owners. That would go a long way toward restoring customer confidence.
    • Grumpy Bear
      OCI, not when but why?

      By Grumpy Bear · Posted

      Without exception but then I'm the odd duck, right? I know what goes into that test, how it is calculated and thus how to beat it. But EPA values are often not beaten by the general public and the government has in past years adjusted the means and methods to come to those values to more closely approximate "Joe Average".    The only real trick to beating that EPA average is don't drive like "Joe Average".    It's the same method you used to profit from "Economic Migration" and in doing so beat the 'stats'. But you, like me, are not "Joe Average".     The thing you don't seem to grasp is this "Purchasing Power Index" isn't forward looking. It doesn't predict what it going to be but looks backward and states what it was. They are not telling us what the THINK, they are telling us what they MEASURED. Example:    Wife says "I'm going to lose 40 pounds by Christmas". May she does, maybe she doesn't but the doctors office who weighed her when she made that statement and again at Christmas only REPORTS what the RESULT was. You and I can banter about what was possible and what aunt Tilly did till the cows come home but the result is the result. Arguing otherwise is.....irrational. That's all I'm saying. This isn't about:      What you are calling a 'Statistic' is a RESULT not a CALCUATION and as a result the RULE. Like gravity as a rule, it can not be broken. 
    • MASONV88888888
      Rattle in the rear!

      By MASONV88888888 · Posted

      Just wanted to say thank you for posting this. Years later, your thread is still helping Silverado owners.   I bought my 2025 Silverado 1500 in January 2025, and I've had what feels like the exact same rattle since day one. After reading your findings, I believe my truck has the same issue with the cable carrier contacting the rear sliding window. To be honest, I had pretty much given up on pursuing the issue. It wasn't until I recently drove another brand's pickup that I realized just how quiet their cabin was—and how noisy mine has been all along. On my truck, the rattle happens on almost any paved road, gets even worse on rougher pavement, and I can even hear it during braking and acceleration.   I actually referenced your thread when submitting my case to GM, hoping they'll recognize this as a recurring issue instead of treating it as an isolated incident. The reason I reached out to GM first is because my dealership told me they would need to keep the truck for at least two days just to diagnose the problem. I was concerned that even after two days, they still might not be able to identify the source of the rattle before giving the truck back to me. I had also asked a few dealerships about this issue during previous service visits, but none of them seemed to know what was causing it or had a solution. That's why I decided to contact GM directly first, hoping they might already have an official repair procedure or guidance for this issue.   I also hope GM eventually comes up with an official fix for this problem. I have a feeling there are many Silverado owners experiencing the same rattle, but most either choose to live with it or simply don't know what the cause is.   Really appreciate you taking the time to document your diagnosis. Your post is still making a difference years later.
    • Buckwild27
      Gas Prices

      By Buckwild27 · Posted

      I have 2 choices. 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...