Ubs And Abs Operation; Normal Braking (Abs Not Activated And Ubs Not Activated) - Yamaha R1 Series 2015 Service Manual

• The ABS performs a self-diagnosis test for a few seconds each time the vehicle first starts off after the
main switch was turned on. During this test, a "clicking" noise can be heard from under the seat, and
if the brake lever or brake pedal is even slightly operated, a vibration can be felt at the lever and pedal,
but these do not indicate a malfunction.
1. Software operation flow
2. Main switch "ON"
3. Initialize
4. Self-diagnosis (when static)
EAS30854

UBS AND ABS OPERATION

The ABS hydraulic circuit consists of two systems: one for the front wheel and one for the rear wheel.

Normal braking (ABS not activated and UBS not activated)

Front brakes:
When the ABS is not activated, the inlet solenoid valve is open and the outlet solenoid valve is closed
because a control signal has not been transmitted from the ABS ECU. Therefore, when the brake lever
is squeezed, the hydraulic pressure in the front brake master cylinder increases and the brake fluid is
sent to the front brake calipers. At this time, the hydraulic pump check valve is closed. The front brake
master cylinder directly pressurizes the front brake calipers during normal braking. When the brake le-
ver is released, the brake fluid in the front brake calipers returns to the front brake master cylinder.
Rear brake:
When the ABS is not activated, the inlet solenoid valve and separation solenoid valve are open and the
outlet solenoid valve and shuttle solenoid valve are closed because a control signal has not been trans-
mitted from the ABS ECU. Therefore, when the brake pedal is depressed, the hydraulic pressure in the
rear brake master cylinder increases and the brake fluid is sent to the rear brake caliper. At this time,
the hydraulic pump check valve is closed. The rear brake master cylinder directly pressurizes the rear
brake caliper during normal braking. When the brake pedal is released, the brake fluid in the rear brake
caliper returns to the rear brake master cylinder.
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5. Self-diagnosis (when riding)
6. Receive signals
7. Control operation
8. Depressurize/pressurize
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