HAC stands for hill-start assist control. It is a safety feature that holds brake pressure for a few seconds after the driver releases the brake pedal on a steep grade. This gives the driver time to transition their foot to the accelerator and engage the clutch or torque converter without the vehicle drifting backward.
Heard on the job
The customer says the HAC is acting up, rolling back on the driveway before the throttle catches.
Also heard as
- hill start assist
- hill holder