Same situation occurred twice. I was in the car at a red light. Car had been stopped for about a minute. Was on a slight decline, engine brake was engaged to hold car in position. Car was stationary completely. Suddenly tons of warning lights flash on the dash board 'One pedal driving unavailable', 'Service ESC', 'Service trailer brake system', 'Service active steering system', '4wd unavailable', service driver assist system , 'Speed limited to 36 mph'. First time this happened was June 2023. Dealer was unable to find the source of the problem but reported that the car was working fine and gave it back to me. The second time was a 10/1/2024. I was able to drive slowly to a parking lot, turn the car off, wait a bit and turn it back on which seemed to reset the warnings. Car is currently at a different dealer and they tell me that unless it happens while they are in the car, they cannot diagnose anything. If this were to happen while driving, it could be very dangerous as the Hummer is a very large heavy vehicle so to lose driving systems in motion is quite a scary thing. Having it happen while stopped is bad since the car doesn't operate normally, steering is erratic and the suspension controls non-existent which impacts safety even with speed limited to 36. The car is available to be inspected as needed.
NHTSA ODI 11621197