This Dealer Bulletin on JL4 option

Team Corvette has done it again - developed another exciting performance system that will further enhance the Corvette driving experience. Get ready for Active Handling!

Early in the 1998 calendar year, Corvette's new Active System (AHS) debut's as an option on all Corvette models. AHS is truly the next step in the evolution of Corvette's ABS and Traction control systems. In simple terms, it helps correct the difference between the driver's intended direction for the vehicle during a turn and its actual direction.

To measure the driver's intended cornering direction, AHS uses several sensors which detect steering wheel angle, individual wheel speed, accelerator pedal position, brake switch and master brake cylinder pressure.

AHS uses the information gained from these sensors to determine the driver's desired yaw rate and speed. Yaw rate is the speed at which the car rotates as it corners. AHS also measures the vehicle's actual yaw rate and lateral acceleration using two new and specific transducers - an accelerometer and a yaw rate sensor.

When there is a significant difference between how the driver intends to corner and how the car actually is cornering, AHS will automatically apply any of the vehicle's brakes to assist in correcting the situation. A real-world example of this would be a sudden lane change on a wet road of to avoid an unexpected hazard, like a large pothole.

A good analogy, in concept, is that AHS is similar to steering a canoe. If a front of a canoe starts turning to the right, it can be brought back on course by dipping a paddle into the water on the left to act as a rudder and brake.

Condition	What it Means	AHS Action

Oversteer	Back end of the car is "loose"	Applies the front brake on the outside of the turn.

Understeer	Car "pushes" into a turn	Applies rear brake on the inside of the turn.

For those who are involved in Gymkhana or autocrats competitions, Corvette's AHS system offers a Competitive Driving Mode. It deactivates the Traction Control part of the system to allow for wheel-spin and acceleration - conditions that highly-skilled drivers sometimes find useful on the track.
Chevrolet recommends against selecting the Competitive Mode for street use.

Remember, the overall effectiveness of AHS is directly related to available tire traction and the aggressiveness of a given maneuver. AHS is designed to work with existing traction to assist the driver, but it cannot overcome the laws of physics.

AHS only reacts in extreme situations. When AHS activates, it is a clear signal that the driver is exceeding the vehicle's or the tire's limits.