When TCS Is Inactive
The TCS solenoid valve (OUT) and ABS solenoid valve (IN) are open while the TCS solenoid valve IN and ABS solenoid valve (OUT) are closed. If brake pedal is depressed, brake fluid pressure in the master cylinder flows through the TCS solenoid valve (OUT), check valve (1) and ABS solenoid valve (IN) to appropriate wheel cylinder, applying brakes. If the brake pedal is released, brake fluid pressure in the master cylinder falls, and the fluid returns through the ABS solenoid valve (IN), check valve (2) and TCS solenoid valve (OUT) to the master cylinder, releasing the brake. See Fig 1 .