AT4 service brake assist

[Shaker]

Power assisted brakes failed in the drive-thru this morning, almost rear ended the guy in front of me. Basically power brakes became manual brakes. Drove into work and called the dealer. After sitting off for 30 minutes I drove to the dealer and the brakes seemed to work properly. Check engine light remained on. Dealer found a bulletin, but the solution was noted as they don't have one. Great to know my brakes could become manual brakes at any minute. 1300 miles on the odometer.

[flowbytwo]

Wow. That’s serious. As in life threatening—easy to imagine scenarios with more speed where something like that would be very bad. I will be very interested to hear how this turns out given I should have the exact same truck in another week or so. 

[Sierra Dan]

Must be something relating to the new electronic-hydro braking, as they did away with the vacuum pump that K2 had.

[GMCustomerService]

On 11/21/2018 at 8:39 PM, Shaker said:

Power assisted brakes failed in the drive-thru this morning, almost rear ended the guy in front of me. Basically power brakes became manual brakes. Drove into work and called the dealer. After sitting off for 30 minutes I drove to the dealer and the brakes seemed to work properly. Check engine light remained on. Dealer found a bulletin, but the solution was noted as they don't have one. Great to know my brakes could become manual brakes at any minute. 1300 miles on the odometer.

Hey, Shaker. I'm sorry to hear about this recent brake situation associated with your AT4. If you'd like to further discuss your concern, feel free to send us a private message. Thanks! 

 

Anthony J.

 

[Shaker]

If anyone was curious bulletin #PIT5638 and code #C058E. The issue hasn't returned, but I'll let you know if it does.

[Jason Gullotta]

Had the same issue. Dealer reset the code, but like you said it's still a possible issue. 

[AT4guy]

I just got my AT4 2 weeks ago. 100 miles into the truck check engine light came on. Took to dealer. Code came up master cylinder for brakes was having an electrical issue. Light went off code cleared. 600 miles later engine light on again this time with a notification service brake assist. Took to dealer had to replace master cylinder and reprogram my instrument cluster as it was blinking on and off while driving. 

 

Driving the truck 300 miles so far so good since shop “fixed” and replaced master cylinder on a brand new truck. Said it was a defective part nothing wrong with truck. We will see. I’m definitely trading in before 36k miles.  This has kinda shaken my faith in GMC. I have always driven sierras had a 2015 that was amazing.  This one “top of the line” AT4 not so much. 

[AT4guy]

I understand issues come about with any truck or vehicle but when you charge $60,000 for a truck you need to make dang sure your customers aren’t spending the first 1,000 to 2,000 miles going from home to dealers service shop. IMO. You can’t tell me no one knew about the issues and just pushed the truck out anyway. These guys are experts. They make billions off of expertise in design and engineering. They knew they had and issue if this many people are having this brake code come up. I work damn hard for my money and putting it into a truck I’ve already had in the shop 2 times and before it’s even close to being time for an oil change is a little subpar to say the very least. Don’t get me wrong. My dealer has done their best to fix the issue but in hindsight I don’t know that I would’ve given so much money to this truck knowing the issues I’m having now. Because now I’m super paranoid about something else going wrong. I know under warranty gmc will take care of me but I wanted to keep this truck for a while. Not going to be that way now. 

[AT4guy]

Let me shut up and say one last bit. I love absolutely love my AT4. Drives great looks amazing rough rugged and the 5.3 has more than enough power for my use. The heads up display and camera mirror is genius unlike in any other truck. I literally have been researching and watching news reviews reports on this since March when they were shown in New York. I guess having this issue affect my truck less than 500 miles into it made me sour. But without the master cylinder issue , this truck has been everything is hoped it would be. 

[txsokie]

Setting at the dealer right now.  Bought a new AT 4 yesterday. Started it up this morning and the service brake assist light pops up. 

[ish]

I'm curious to know what the build month for those who are affected by this.

 

[txsokie]

Mine was built last week of October. The dealer decided it was air in the brake line left over from the build .  Bleed the brakes added new fluid and reset the code.  So far so good but time will tell.

[CaliDenali]

Just picked up my truck for “service break assist” message. Like other said dealer cleared code and have no further info. Dealer gave me the bulliten and gave me GM CS number. I already called and filed a complaint.

 

IMO no way any 57k (mine isn’t fully decked out LOL) AT4 should be having these issues at 217 miles. 1-866-522-9559 is the CS number. Of course my VIN didn’t come back to a recall or defect, I laughed and said she was right because there isn’t a fix for the problem. I will continue to follow up on this with you all. 

[j-ten-ner]

On 2018-11-29 at 9:49 PM, AT4guy said:

I understand issues come about with any truck or vehicle but when you charge $60,000 for a truck you need to make dang sure your customers aren’t spending the first 1,000 to 2,000 miles going from home to dealers service shop. IMO. You can’t tell me no one knew about the issues and just pushed the truck out anyway. These guys are experts. They make billions off of expertise in design and engineering. They knew they had and issue if this many people are having this brake code come up. I work damn hard for my money and putting it into a truck I’ve already had in the shop 2 times and before it’s even close to being time for an oil change is a little subpar to say the very least. Don’t get me wrong. My dealer has done their best to fix the issue but in hindsight I don’t know that I would’ve given so much money to this truck knowing the issues I’m having now. Because now I’m super paranoid about something else going wrong. I know under warranty gmc will take care of me but I wanted to keep this truck for a while. Not going to be that way now. 

 

On 2018-11-30 at 4:56 AM, AT4guy said:

Let me shut up and say one last bit. I love absolutely love my AT4. Drives great looks amazing rough rugged and the 5.3 has more than enough power for my use. The heads up display and camera mirror is genius unlike in any other truck. I literally have been researching and watching news reviews reports on this since March when they were shown in New York. I guess having this issue affect my truck less than 500 miles into it made me sour. But without the master cylinder issue , this truck has been everything is hoped it would be. 

lol

 

That's why I want to have one of the trucks they've used for Zillions of miles of testing.

They must be flawless.

 

so long

j-ten-ner

[SS502]

On 12/4/2018 at 8:30 PM, j-ten-ner said:

 

lol

 

That's why I want to have one of the trucks they've used for Zillions of miles of testing.

They must be flawless.

 

so long

j-ten-ner

Won’t ever happen, they are using customers for the R&D...