ESP - Description

1.9 JTD 8V · from 06/04, from 09/03

Description

The electronic anti-lock brake system (BOSCH 5.7 ABS with ASR) governs braking pressure sent to the wheels and prevents loss of grip under all tyre and road surface conditions.

This is combined with an ESP (Electronic Stability Program) system, which controls vehicle stability by modulating drive torque and braking the wheels differentially, if there is a loss of grip, thus helping to return the car to its correct trajectory.

The ESP system acts on the engine and brakes to generate a stabilising torque when the ABS sensors detect conditions that could lead to the vehicle slipping.

The ESP system includes the following specific components over and above those of the ABS:

• a sensor which detects the steering wheel position (steering sensor);
• a sensor which detects the vehicle's rotation around the vertical axis and side acceleration (centrifugal force) (yaw sensor);
• a sensor that detects pressure on the hydraulic ABS unit (pressure sensor)

The ESP system is always connected to the ASR system.

The ASR system increases vehicle stability and active safety by controlling drive wheel slip. If slip is caused by excessive power transmission, it cuts in to reduce engine power through communication with the engine management control unit. if slip is detected at a single wheel, the system cuts in to brake the slipping wheel by acting on the modulation solenoid.

ASR comes on automatically whenever the engine is started. The system can be deactivated by operating a button in the dashboard.

When the system is off, an LED on the button comes on at the same time as a warning light on the control panel.

The ESP, on the other hand, switches on automatically each time the engine is started up and cannot be switched off.

ASR/ESP warning light: the warning light flashes when the system cuts in to notifiy the driver that the ASR system has cut in due to road surface grip conditions.

When th econtrol unit detects an error in the ASR function or the ESP function, it lights up the warning light constantly.

As far as the ABS function is concerned, See E7020 ABS.

For more details, Characteristic of working principle 3340 A(B.S. ANTI-LOCK BRAKING SYSTEM .)

The supply lines for the control unit and the various system components (sensors and actuators) are protected by a special maxifuse, located near the control unit, and by a fuse in the engine compartment in the relay and fuse box.

The ASR off button is protected by a special shunt fuse, located next to the junction unit.