Yamaha XT1200Z(Z) 2010 Service Manual page 17

When the brake lever is squeezed, the front brake master cylinder pressure sensor in the hydraulic unit
detects the hydraulic pressure. The ABS ECU calculates the appropriate rear brake force according to
the detected hydraulic pressure and sends a signal to the rear brake hydraulic pump. The hydraulic
pump pressurizes the rear brake caliper using electronic control to operate the rear brake.
TIP
• If the brake pedal is depressed while the brake lever is being squeezed, the brake pedal may feel hard
due to the operation of the UBS, but this does not indicate a malfunction.
• If the rider squeezes the brake lever while resting their foot on the brake pedal, a vibration can be felt
at the brake pedal due to the operation of the UBS, but this does not indicate a malfunction.
ECA23P1054
NOTICE
• The UBS does not operate before the vehicle starts off.
• If the vehicle is stopped by operating the brake lever only, the brake force due to the operation
of the UBS will be maintained while the brake lever is squeezed. However, if the brake lever is
released, then squeezed again, the UBS will not operate.
ECA23P1055
NOTICE
• The unified brake system is a system to assist the brake operation. However, both the brake
lever and the brake pedal must be operated for maximum braking effect.
• Because the balance between the front brake calipers and the rear brake caliper in the unified
brake system is determined electronically, be sure to use the specified brake pads.
• Each set of brake pads should be checked individually and replaced if necessary.
When vehicle is stopped using brake lever only
A
a
b
A. Deceleration
a. Input
b. Automatic pressurization
UBS hydraulic pressure map
The appropriate hydraulic pressure is distributed according to the load being carried by the vehicle. See
figure "A".
The coefficient is set according to the vehicle speed when the brake input starts and remains constant
until the brake input stops. When the brakes are operated continuously to slow the vehicle, the coeffi-
cient (UBS brake force) does not decrease together with the vehicle speed. See figure "B".
B
c
d
B. Vehicle stopped
c. Input maintained
d. Pressurization maintained
1-8
FEATURES
C
e
f
C. Brake lever released, then
squeezed again, after vehicle
stops
e. Brake lever released, then
squeezed again
f. No automatic pressurization