GM Service Manual Online
For 1990-2009 cars only

This vehicle has a Hill Start Assist (HSA) feature, which may be useful when the vehicle is stopped on a grade. This feature is designed to prevent the vehicle from rolling, either forward or rearward, during vehicle drive off. After the vehicle is stopped on an incline, push the brake pedal completely to the floor to activate Hill Start Assist. When the system activates, a chime will sound and the HSA ON message will be displayed.

Letting off the brake pedal slightly or applying the accelerator pedal to disengage Hill Start Assist gives the driver two seconds to pull forward or back up before the vehicle starts to roll. Lightly ease off the brake pedal to disengage Hill Start Assist. The brakes will automatically be held for a maximum of two seconds while the driver switches from applying the brakes to pushing the accelerator pedal.

When Hill Start Assist is active, the driver might experience a "hard pedal." This is normal and does not affect safe brake operation.

On steeper hills, Hill Start Assist will only activate if the driver tries to move the vehicle up the hill. It will not activate if the vehicle is in a drive gear and facing downhill or if the vehicle is facing uphill and in R (Reverse).