- ABS - Anti-lock Braking System;
- EBD - Electronic Brakeforce Distribution System;
- TCS - Traction Control System;
- VSES - Vehicle Stability Electronics System.
The operation of the specified functions is ensured by:
- ABS pump - part of the pressure modulator valve in the brake system. The ABS pump is active during ABS, VSES and main braking.
- booster valve.
- vacuum sensor in the brake booster. Based on the sensor signals, the brake control unit decides to pre-charge the brake system.
- the brake pressure modulator valve controls the hydraulic pressure to the brake of each wheel independently.
- lateral acceleration sensor - the brake control unit determines the centrifugal acceleration of the vehicle using the sensor signals. The lateral acceleration sensor is housed in the same housing as the vehicle rotation sensor around the vertical axis.
- master cylinder pressure sensor.
- brake booster valve. The valve helps to create a 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 sensor signals, the brake control unit determines the speed of rotation of the steering wheel and the center of rotation of the vehicle.
- tCS system switch.
By pressing the switch, the driver enables or disables the functions of the VSES and TCS systems:
- wheel speed sensors. Based on the sensor signals, the brake control unit calculates a strategy to prevent wheel locking (individually).
- vehicle course deviation sensor. The sensor signals determine whether the front or rear axle is skidding.
The brake control unit program includes a self-diagnosis function for the system. The control unit can detect many faults immediately after the ignition is turned on.
However, faults in the valve windings or electric motors of the system cannot be detected until a signal is given to activate the unit. Therefore, diagnostics are carried out at the beginning of each ignition cycle to confirm the operability of the system before allowing the performance of certain functions of the braking system. Diagnostics are carried out in two phases: after the ignition is turned on and after the vehicle reaches a speed of 12 km / h. In the second phase, when low pressure is detected in the main brake cylinder, the control unit carries out an additional check, during which the driver can feel an instantaneous "hard" pedal.
When the vehicle speed exceeds 25 km/h, full initialization of the VSES system sensors begins. Initialization continues for 3 km on a road with bends or 1 km on a straight road. If initialization is attempted on a very winding road or with a strong variable crosswind, a system malfunction may be recorded and the corresponding information will be displayed on the driver's display.
Diagnostic trouble codes are listed in the "Trouble Codes" chapter.
The braking system uses information indicators such as:
- brake system warning indicator. The indicator lights up when:
- the parking brake is applied (blinking at a frequency of 2 times per second);
- there is a low brake fluid level;
- the lamps are being tested for functionality;
- a malfunction in the ABS system is detected.
- ABS indicator. The indicator lights up when:
- ABS malfunction detected;
- the lamps are being tested for functionality;
- 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 system failure is detected;
- the driver forcibly disabled the VSES system.
(The material was created based on information from the website: «chevyman»)