The problem first arose in June 2023 with a different car, 2022 CT4V VIN [XXX] . I was driving and suddenly, all the dashboard lights went on and the brakes stopped working. There was no pressure on the pedal. I was able to roll to a stop without incident. I turned the car off and back on again and the brakes worked but the check engine light was still on. I was able to limp the mile back to my house. After almost 6 weeks at the dealer, I was told they replaced a brake module and the car was fine. On [XXX], it happened again. It was towed to the dealer and I refused to drive it again. The car had about 2400 miles on it. They took it back, although claiming nothing was wrong, and I bought the CT4V Blackwing 2023. On [XXX], it happened in the new car (500 miles on it). The dashboard lit up, the brakes wouldn't work, although this time instead of no pressure on the pedal, it was hard as a rock. After turning it on and off again, the brakes worked but the speed was restricted and other things in the car did not seem to be working correctly. The check engine light was also on. The dealership towed it. They told me they could not recreate the problem. Weeks later, I was told that an engineer from GM was looking at it. I received a call from some customer support department person who eventually told me that there was nothing wrong with the car, that the brake failure was a result of the Allstate Milewise device that was plugged in and they would not do anything for me. My husband has a Milewise in his Chevy truck with no issues. I found a forum online discussing this problem which has apparently happened to numerous people in CT4V and Blackwings. I also spoke to Allstate which does not have any reported problems with the device. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA ODI 11564719