Over time, the transmission control valve could wear and lose pressure. If this happens, the transmission could shift harshly and could cause the wheels to lock up.
Safety Risk
Wheels that lock suddenly could cause a loss of control and increase the risk of a crash.
Corrective Actions
General Motors will notify owners by mail and advise you to take your vehicle to a dealership to update the transmission control module software to detect excess wear in advance of a wheel lock up. If detected, a service engine light would turn on, a message would display in the instrument panel and the vehicle would be limited to fifth gear.