Just what is stability control? And why do we have it? My GMC pickup caught me totally off guard when I was going up a familiar hill on a damp morning recently. I was accelerating normally when the rear end started to break loose. Before I could react, however, the StabiliTrak light started to flash, the rpms dropped, and I could hear the anti-lock brake system (ABS) pump running and the solenoids cycling. I never hit the brakes but my immediate reaction was to let off the gas... but by then my truck had already returned to the direction that I’d always intended. Almost before I lost control, I had it back again.