Kia Optima: HAC (Hill-start assist control)
Hill start Assist Control is a comfort function. The main intend is to prevent the vehicle from rolling backwards while driving off uphill on an inclined surface. HAC holds the braking pressure builtup by driver during stopping procedure for 2 seconds after releasing brake pedal.
During the pressure-hold period, the driver has enough time to press the accelerator pedal to drive off.
The braking pressure is reduced as soon as the system detects the driver’s intention to drive off.
The HAC is usually activated only for 2 seconds. The driver should be careful from the rolling backward causing the accident with behind objects or human, when the driver may feel the unintended rolling backward while driving off on hill due to insufficient brake hold pressure built-up by driver during stopping procedure.
- The HAC does not operate when the transaxle shift lever is in the P (Park) or N (Neutral) position.
- The HAC activates even though the ESP is off but it does not activate when the ESP has malfunctioned.