Hard breaks

[Beckiee]

My 17 year old daughter drives a 2023 z71 trail boss LT. It has about 20,000 miles on. Last Thursday come home from school the breaks became very hard for her to press down and she was unable to break to turn into our neighborhood. 3 messages appeared on the dash: ESC service, failure to break at 62 mph, and trailer break failure. She eventually stopped with lots on force to press the break. It took her about a mile to come to a stop. Very scary. After the truck stopped she turned it off. She then turned it back on and it worked normal. I drove the truck back to our house and immediately called Chevy dealership for an appt. We got it in the next day. That evening drive to the dealership to drop off the truck goes dead at the red light. Turns off, lights go dark, hazard light go off. Can’t restart it. Just dead. My husband openers the door and throws up his hands. The opening of the door resets everything and able to start the truck again. The next day the dealership calls and says it’s ready for pick up. Can’t find anything wrong with it and no codes. The day this happened I already watched several YouTube videos about this happening because of a vacuum pump failure. Tech said 2023 doesn’t have a vacuum pump, it’s electronic. We refused picking it up bc it would not break while driving and nothing had been done to resolve. They were going to look further into it and drive it over the weekend which didn’t happen. Come today, still nothing wrong but they did the software recall that was for the dash light not coming on the dash when the breaks don’t work because of low break fluid, as I understand it. The break fluid is normal and nothing found. We asked about the truck dying at the red light and he said it has the idle stop feature is on. NOT THE SAME. It went completely dead. No light, radio nothing! We are at a loss. Anyone else have this issue? Or know what the prob is so we can fix it?

 

[Stormin08]

that is a first for me hearing of these issues...the global B platform is having some serious issues with communications within the vehicle.
it sucks, but you may want to look around at the wiring, mainly large connectors as those seem to have the most issues

the ECM is behind the front driver side wheel liner, below the headlight area...start poking and tugging. My 23, when new Oct. 23 had less than 500 miles and became a total brick, spent over a week at eh dealer waiting for a specialist to arrive and reflash all comm devices

 

[Jlando]

that is a first for me hearing of these issues...the global B platform is having some serious issues with communications within the vehicle.
it sucks, but you may want to look around at the wiring, mainly large connectors as those seem to have the most issues

the ECM is behind the front driver side wheel liner, below the headlight area...start poking and tugging. My 23, when new Oct. 23 had less than 500 miles and became a total brick, spent over a week at eh dealer waiting for a specialist to arrive and reflash all comm devices

What was the issue with your 23? My 24 TB LT has been to the Dealer for over a week now waiting on a GM specialist to look at it. Apparently my TB is losing all communication. Keep in mind this has been an ongoing issue and been to the Dealer numerous times, see below.
Engine light illuminated, Driver Information center started scrolling the numerous messages to include the following.

• Service Transmission
• Service 4 Wheel Drive
• Service Traction Control
• Service Brake System (ABS)
• Reduce Acceleration Drive Safely
• Put Hands on Steering Wheel

Something new I noticed was that numerous warning lights illuminated on the Instrument Cluster during the drive to the dealership. If I remember correctly the warning lights observed were as follows.

• Tire Pressure Monitor
• Four-Wheel-Drive Light
• Stop/Start
• Antilock Brake System (ABS)
• Traction Off Light
• Check Engine

Note – None of the above listed lights were blinking and/or flashing.

I had also noticed during this drive that the transmission would not upshift into a higher gear. I had to maintain 25mph. The other thing noticed was the HVAC fan turned on high, turned it off but it turned right back on. Had to do this several times on the way to the dealership. The fan or blower motor would not stay off.

 

[Stormin08]

it sounds to me like the vehicle went into a full blown LIMP mode. they wont totally stop your vehicle for protection and safety...but functions are limited.
the HVAC default has been in design for years, any car that the HVAC fails....fails into a mode that keeps the windscreen clear

MY 23, was performing an AUTO UPDATE in the back ground, i did not know that was happening....powered off, exited vehicle. when i returned, the vehicle would start but nothing would talk or function. TOTAL BRICK ! since that day, my dealer service writer...informed me to turn off all auto update features, watch for updates...and see if I NEEDED THAT update. so far, i have had no issues with vehicle performance

 

[Stormin08]

one thing i do want to mention...i have 1 of about 4000 fleet trucks at work.
my last one, a 2017 Silverado, had an issue where the STEERING RACK or RACK MODULE was failing. what i noticed was this...
twice while turning into a parking spot, the truck locked the wheel mid turn, brakes got super hard and all lights and controls went hay wire.
it did this 1 time mid drive getting off an exit rap, slight turn of the wheel and BOOM>>> did it again. very much like a dead short to ground and causing all sorts of issues with electronics.

 

[2KWIK2C]

So glad I got a '21. No issues.

 

[Jlando]

it sounds to me like the vehicle went into a full blown LIMP mode. they wont totally stop your vehicle for protection and safety...but functions are limited.
the HVAC default has been in design for years, any car that the HVAC fails....fails into a mode that keeps the windscreen clear

MY 23, was performing an AUTO UPDATE in the back ground, i did not know that was happening....powered off, exited vehicle. when i returned, the vehicle would start but nothing would talk or function. TOTAL BRICK ! since that day, my dealer service writer...informed me to turn off all auto update features, watch for updates...and see if I NEEDED THAT update. so far, i have had no issues with vehicle performance

Makes some sense on full Limp mode and HVAC fan coming on high to keep windscreen clear. Now to determine why vehicle is going into full blown LIMP mode! I'm going to stop by the Dealer after work this afternoon for an update as I haven't heard anything other than they're waiting on GM assistance last week. Starting to grow a little frustrated. Truck has only 3600 miles on it.