Originally Posted by powertech83
Nahoa is correct, it is constantly on, the car should detects that you are on an uphill.
Maybe in your case, the inclination was not steep enough to trigger the hill-start assist sensor? You can tell if hillstart assist is activated if you lift off the brake pedal on an incline (with auto hold feature turned off) and press it again, the pedal will be stiff as if the auto hold is on.
That's weird cause the hillstart for my car must have not kicked in. Cause it was definitely rolling down like a manual car. I was actually quite surprised when that happen cause even my Toyota would not do that on D(gear).