Service manual

CHAS
43
ABS operation
The ABS hydraulic circuit consists of two systems: the front wheel and rear wheel. The following
describes the front system only.
• Normal braking (ABS not activated)
When the ABS is not activated port D of the solenoid valve is closed because a control signal has
not been transmitted from the ECU (ABS) and port A and port B of the flow control valve are
open. Therefore, when the brake lever is squeezed, the hydraulic pressure in the brake master cylin-
der increases and the brake fluid is sent to the brake caliper via port A and port B.
At this time, the inlet and outlet check valves of the pump close the lines and brake fluid is not sent.
As a result, the brake master cylinder directly pressurizes the brake caliper during normal braking.
When the brake lever is released, the brake fluid in the brake caliper returns to the brake master cyl-
inder via port A and port B.
ANTI-LOCK BRAKE SYSTEM (ABS)
Brake master cyl-
inder
Brake light switch
ABS motor
Pump
Buffer chamber
Flow control valve
Port A
Spool
Port B
Orifice
Port D
Solenoid valve
Port C
Brake caliper
ECU (ABS)
ABS warning light
Brake fluid pres-
sure
Time
Repressurizing