Yamaha XP500 Service Manual page 23

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 A of the solenoid valve is closed because a control signal has
not been transmitted from the ECU (ABS) and port A 7 and port B 9 of the flow control valve are
open. Therefore, when the brake lever is squeezed, the hydraulic pressure in the brake master cyl-
inder 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.
FEATURES
1 Brake master cyl-
inder
2 Brake light switch
3 ABS motor
4 Pump
5 Buffer chamber
6 Flow control valve
7 Port A
8 Spool
9 Port B
0 Orifice
1 - 12
GEN
INFO
A Port D
B Solenoid valve
C Port C
D Brake caliper
E ECU (ABS)
F ABS warning light
G Brake fluid pres-
sure
H Time
I Repressurizing