Enhanced Stability Control (ESC)
Warning: Electronic stability control is intended only as an aid for a conscientious and alert driver. Carefully read the information in this manual to understand this system and its limitations. ESC is not a substitute for safe driving procedures. Failure to drive safely, and use the system properly, could result in personal injury and/or death and property damage.
Notice: Changing or modifying the location of the ESC sensor or reconfiguring the vehicle, such as by changing the wheelbase or adding axles, can change the performance of the enhanced stability control system and may result in product or property damage and personal injury.
An amber-colored indicator light, shown in Fig., indicates that the vehicle is equipped with electronic stability system components.
The indicator light illuminates whenever the ESC system intervenes.
Fig. 1, ATC/Stability Indicator Lamp
The roll stability system uses a lateral-acceleration sensor that monitors rollover risk. Shortly after a curve, lane change, or other driving maneuver that results in a rollover-risk detection, a dash warning light illuminates. The purpose is to advise the driver that the previous maneuver produced a rollover risk.
The roll stability control system, within ESC, automatically reduces engine power, applies the engine brake, and/or applies the tractor and trailer brakes when the acceleration sensor detects that the vehicle is at risk of rolling over.
ESC also has the capability of complete directional stability (yaw control) in oversteer and understeer conditions to reduce the likelihood of drift-out or jackknife. The system determines where the driver is attempting to steer the vehicle and how much brake demand is required in order to more precisely control the vehicle in an emergency situation.
ESC works by constantly comparing the driver’s intention with the vehicle's actual behavior. The system does this by monitoring systems such as wheel speed, steering angle, yaw rate, lateral acceleration, throttle position, and brake application. A central microcomputer analyzes the collected data and triggers a response to keep the vehicle on course when an unstable condition is detected.
When the system detects that the vehicle is at risk of oversteering or understeering, it applies individual tractor wheel end brakes and trailer brakes, activates the engine retarder (if equipped), and/or decreases engine power, depending on the severity. As a result, the driver has full control over the vehicle until the system detects a potential risk and intervenes accordingly. ESC operates automatically; the driver does not monitor or activate the system.