Electronic Stability Program or ESP is the name given by the Chrysler corporation to the electronic driver’s aids that are used to help motorists keep their vehicles under control when faced with inclement weather conditions or extreme driving situations. Introduced in 2004, ESP was first available exclusively on the Chrysler 300 and Dodge Magnum. The reason these vehicles were chosen to roll out the technology is because at the time, Chrysler had merged with Mercedes and formed the DaimlerChrysler corporation, and the LX platform upon which they were based was in fact adapted from the Mercedes-Benz E-Class. Mercedes had been perfecting their ESP technology since 1995, and the years of development directly benefited these Chrysler products. The German auto manufacturer had long claimed that the Electronic Stability Program had played a significant role in reducing the number of serious accidents that their vehicles had been involved in. In 2006, Chrysler announced that they would be installing the system on an additional 1.2 million vehicles, with the eventual goal of covering 70 percent of their vehicle lineup.
How ESP works
The Electronic Stability Program from Chrysler is a fairly complex piece of engineering. The aim of this system was to move beyond a safety program which was only active during acceleration. ESP is armed as soon as the vehicle is started, and sensor data is gathered at all times. This data is fed into an active computer model which compares the standard behavior of the vehicle’s driver against the actual driving situation as reported by the sensor information. The model is adaptive and learns the driving habits of the vehicle owner, using this information to generate the baseline of safe values to use for comparison purposes. Through this methodology, the ESP system is designed to rapidly react to any deviations between expected values and the condition of the vehicle. This computer model sets the Chrysler Electronic Stability Program apart from other, more basic brake and throttle management stability control systems.
Information such as vehicle speed, braking intensity, pitch and yaw and traction are all taken into consideration. Wheel speed is determined by the same sensors that are used to help the anti-lock braking system (ABS) system choose where braking force should be applied. Steering angle is measured by a sensor in the steering column that notes the position of the steering wheel relative to the actual direction of the vehicle as determined by the yaw sensor. A sensor measuring the lateral acceleration of a vehicle is used to ascertain if the vehicle is in the middle of a skid or not. All of these factors are calculated extremely rapidly by the central processing unit of the ESP system, since at highway speeds even milliseconds can result in a significant amount of distance traveled.
How ESP can help
If the Electronic Stability Program determines that intervention is needed, it can respond in a variety of ways to ensure the continued safe operation of the vehicle. ESP can reduce engine power, thus eliminating wheel spin and slowing down the vehicle in a low-traction situation. It can also take multiple steps to correct a skid or slide, such as individually applying the brakes to each wheel in order to prevent the vehicle from rotating or building enough inertia to roll over. It can also take the extreme option of both applying the brakes and cutting power to bring the vehicle to a complete stop, should it decide that conditions are too treacherous to continue driving.
A common misconception is that stability control programs use the ABS system in order to control the braking pressure at each wheel. In reality, ESP must increase braking pressure individually, while an ABS system reduces the braking pressure of an individual wheel while maintaining uniform pressure for the remaining brakes. This means that the Electronic Stability Program requires a separate brake modulator.
ESP is now a common feature in Chrysler and Dodge vehicles, and in most of these cars it cannot be completely disabled. Unlike other stability programs on the market, pushing the button on the dash to ‘deactivate’ the system merely lowers its sensitivity. In the case of extreme wheel spin or radical lateral movement, ESP will kick in to reign the vehicle back under control. In order to completely remove the Electronic Stability Program from the equation, it is necessary to pull a fuse underneath the hood of the car. In response to consumer demand, some of Chrysler’s more performance-oriented vehicles are now being outfitted with an ESP system which does not require such an extreme step in order to be turned off completely.