Yamaha YP250A 1999 Supplementary Service Manual page 41

ANTI-LOCK BRAKE SYSTEM (ABS)
Soft wear operation flow
Turn the main switch on
Initialize
Self diagnosis
(at static)
Self diagnosis
(at riding)
Receive the signals
Control operation
Judge of decompressing /
pressurizing
The operation result is confirmed by the monitor
circuit. Based on the result, the control signals of
hydraulic unit (HU) and fail-safe relay will be is-
sued.
ABS control operation
The ABS control operation performed in ECU is di-
vided into 2 parts as follows.
1
2
These operations will be performed repeating one
time in every 8/1000 seconds. In the case of fail-
ure occurrence, it is stored in the malfunction code
memory allowing easy find and check of failures.
NOTE:
Depending on the type of failure, it will not be re-
corded in the memory. (e.g. battery voltage drop)
8 / 1000
seconds
Hydraulic unit (HU)
This hydraulic unit (HU) 1 is the component to
control the hydraulic pressure of brake system un-
der the signal of ECU, and located beside the bat-
tery box at the center of scooter central part.
33
Hydraulic control
Self diagnosis
CHAS