The affected trucks were built between January 2013 and September 2014. GM estimates that about two percent of the 691,000 are actually affected by the defect. GM notified the NHTSA and its dealerships on June 29, stating that when a fix is available.
According to GM, the problem occurs during actions that require high electrical current, such as low speed turns. The defect can cause temporary low voltage within the trucks’ electrical systems.
When the vehicle’s system voltage drops below 8.8 volts for more than one second, the trucks’ power steering assist is disabled until voltage returns to 9 volts for at least 40 milliseconds, according to GM. The power loss could cause a temporary loss of steering control, even though the issue typically happens within a one-second period, GM notes. Further, other electrical subsystems might also shut down at the same time or just before, temporarily disabling the radio, door locks, air conditioning and cruise control, among other devices.