The electronic stabilization system integrates the anti-lock and traction control systems. ESP additionally measures the speed of the body movement around the vertical axis, acceleration in the transverse plane, pressure in the brake drive system and the angle of rotation of the steered wheels. Based on the data on the angle of rotation of the steered wheels and the speed of the car, the system determines the direction in which the driver intends to move and compares it with the actual direction of movement. If these factors do not match, when the car begins to skid or drift, the stabilization system automatically brakes a certain wheel.
If there is a fault, the electronic control system is automatically switched off, and the control lamps in the instrument cluster light up. In this case, the brake system operates in normal mode.
Fig. 15–1. Location of the anti-lock braking system and electronic stabilization system (ABS/ESP) components on the vehicle: 1 – hydraulic pump; 2 – brake system pressure sensor; 3 – pump relay J105 for Bosch 5.3 system; 4 – electromagnetic relay of valve J106 for Bosch 5.3 system; 5 – hydraulic unit N55 with control unit J104; 6 – control unit J104 for Bosch 5.0 system; 7 – brake fluid level sensor – F34; 8 – Front right ABS sensor rotor; 9 – Front right ABS sensor – G45; 10 – control unit J104 (with ESP); 11 – Steering angle sensor G85 (with ESP); 12 – Switch for TCS/ESP-E132 systems; 13 – steering angle sensor G85; 14 – Parking brake status indicator lamp switch F9; 15 – Rear right ABS sensor rotor; 16 – Rear right ABS sensor – G44; 17 – Rear left ABS sensor – G46; 18 – Rear left ABS sensor rotor; 19 – Lateral acceleration sensor G200; 20 – Status sensor G202; 21 – Pump relay J105 for Bosch 5.3 system; 22 – electromagnetic relay J106 for Bosch 5.3 system; 23 – control lamp K118; 24 – ABS control lamp – K47; 25 – Parking brake status indicator lamp – K14; 26 – TCS/ESP control lamp – K86; 27 – brake light switch F; 28 – Front left ABS sensor rotor; 29 – Front left ABS sensor – G47
The location of the ABS and ESP components on the vehicle and the front axle is shown in Fig. 15–1 and 15–2.
Fig. 15–2. Location of ABS/ESP components on the front axle: 1 – drive shaft with ABS sensor rotor (if the ABS sensor rotor is damaged, the outer joint of the drive shaft must be replaced); 2 – bolt, 10 Nm; 3 – bracket for fixing the ABS sensor wire with a sealing ring; 4 – bolt; 5 – clamping sleeve; 6 – seal; 7 – ABS sensor
[Content source: the specified website AUDImanual]