- ABS - anti-lock braking system;
- EBD - electronic brake force distribution system;
- TCS - traction control;
- VSES - vehicle stability control system.
These functions are provided by:
- The ABS pump is part of the pressure modulator valve in the brake system. The ABS pump is active during ABS, VSES and main braking.
- amplifier valve.
- vacuum sensor in the vacuum brake booster. Based on the signals from the sensor, the brake control unit decides whether to pre-charge the brake system.
- The brake pressure modulator valve controls the hydraulic brake pressure for each wheel independently.
- lateral acceleration sensor - according to the sensor signals, the brake control unit determines the centrifugal acceleration of the vehicle. In the same housing with the lateral acceleration sensor, a vehicle rotation sensor around a vertical axis is installed.
- pressure sensor in the master cylinder.
- brake booster valve. The valve helps create vacuum in the brake booster in case of low vacuum in the booster. The valve is active during emergency braking.
- steering wheel position sensor. Based on the signals from the sensor, the brake control unit determines the speed of the steering wheel and the turning center of the vehicle.
- TCS switch.
By pressing the switch, the driver enables or disables the functions of the VSES and TCS systems:
- wheel speed sensors. Based on the signals from the sensors, the brake control unit calculates a strategy to prevent wheel lock (individually).
- vehicle yaw sensor. According to the sensor signals, the presence of skidding of the front or rear axle is determined.
The program of the braking control unit provides a system self-diagnosis function. The control unit can determine many faults immediately after the ignition is turned on.
However, faults in the valve windings or motors in the system cannot be detected until the node has been signaled to activate. Therefore, diagnostics are carried out at the beginning of each ignition cycle to confirm that the system is working before allowing certain functions of the brake system to be performed. Diagnostics is carried out in two phases: after switching on the ignition and after reaching a vehicle speed of 12 km / h. In the second phase, when low pressure is detected in the master brake cylinder, the control unit conducts an additional check, during which the driver can feel an instant "hard" pedal.
When the vehicle speed exceeds 25 km/h, the full initialization of the VSES sensors begins. The initialization continues for 3 km on a curved road or 1 km on a straight road. If you try to initialize on a very winding road or with variable strong crosswinds, a system malfunction may occur with the corresponding information displayed on the driver display.
Diagnostic trouble codes are listed in the chapter "Fault codes".
The brake system uses informational indicators, such as:
- brake system warning indicator. The indicator lights up when:
- applied parking brake (blinking at a frequency of 2 times per second);
- there is a low level of brake fluid;
- lamps are being tested;
- ABS malfunction is detected.
- ABS indicator. The indicator lights up when:
- a malfunction in the ABS is detected;
- lamps are being tested;
- there is a loss of communication between the instrument cluster and the brake control unit;
- an ABS fault is detected in the previous ignition cycle.
- TCS indicator. The indicator lights up when:
- a failure is detected in the system;
- the driver forcibly disabled the VSES system.