Yamaha Fz6 N Service Manual

							
FEATURES
1-12
WARNING
EWA4S81004
The braking of the vehicle, even in the worst case, is principally executed when the vehicle is 
advancing straight ahead. During a turn, sudden braking is liable to cause a loss of traction 
of the tires. Even in vehicles equipped with ABS, overturning of the vehicle cannot be pre-
vented if it is braked suddenly.
The ABS functions to prevent the tendency of the wheel to lock by controlling the brake fluid pres-
sure. However, if there is a tendency of the wheel to lock on a slippery road surface, due to engine 
braking, the ABS may not be able to prevent the wheel from locking.
WARNING
EWA13870
The ABS controls only the tendency of the wheel to lock caused by applying the brakes. The 
ABS cannot prevent wheel lock on slippery surfaces, such as ice, when it is caused by 
engine braking, even if the ABS is operating.
Electronic ABS features
The Yamaha ABS (anti-lock brake system) has been developed with the most advanced electronic 
technology.
The ABS control is processed with good respon se under various vehicle travel conditions.
The ABS also includes a highly developed self-di agnosis function. The ABS detects any problem 
condition and allows normal braking even if the ABS is not operating properly.
When this occurs, the ABS warning light  on the meter assembly comes on.
The ABS stores the malfunction codes in the me mory of the ABS ECU for easy problem identifica-
tion and troubleshooting.
a. Friction force between the tire and road  surface
b. Brake force c. Side force
d. Slip ratio (%) 
						

							
FEATURES
1-13
ABS block diagram
EAS4S81008
ABS COMPONENT FUNCTIONS
Wheel sensors and wheel sensor rotors
Wheel sensors “1” detect the wheel rotation speed and transmit the wheel rotation signal to the ABS 
ECU.
Each wheel sensor is composed of a permanent  magnet and a hall IC. The wheel sensors are 
installed in the sensor  housing for each wheel.
Sensor rotor “2” is pressed in the inner side of  the front wheel hub and rotate with the wheel.
Sensor rotor “3” is install on the rear hub and rotate  with the wheel. The sensor rotors have 42/front, 
44/rear serrations inside and are installed close to  the wheel sensors. As the sensor rotor rotates, 
the hall element in the hall IC installed in the wheel sensor generates the voltage which is propor-
tional to the magnetic flux density, and the generat ed voltage is processed for waveform shaping in 
the hall IC to output.
The ABS ECU calculates the wheel rotation speed by detecting the frequency of this voltage.
1. Rear brake master cylinder
2. Hydraulic unit
3. Hydraulic pump
4. ABS motor
5. Buffer chamber
6. Hydraulic control valve
7. Front brake master cylinder 8. Rear brake caliper
9. Front brake caliper
10.ABS ECU
11.Rear wheel sensor
12.Front wheel sensor
13.ABS warning light 
						

							
FEATURES
1-14
ABS warning light
The ABS warning light “1” comes on to warn the rider if a malfunction in the ABS occurs.
When the main switch is turned to “ON”, the ABS warning light comes on for 2 seconds, then goes 
off, so that the rider can check if the ABS warning light is disconnected and check if the ABS is oper-
ating properly.
CAUTION:
ECA4S81005
If the rear wheel is raced with the vehicle on the suitable stand, the ABS warning light may 
flash or come on. If this occurs, turn the main switch to “OFF”, then back to “ON”. The ABS 
operation is normal if the ABS warning light comes on for 2 seconds, then goes off.
4. At low speed
5. At high speed
6. Wheel sensor 7. Wheel sensor rotor
8. Voltage
9. Time
A. FZ6-NA/FZ6-SA
B. FZ6-NAHG/FZ6-SAHG 
						

							
FEATURES
1-15
Hydraulic unit
The hydraulic unit “1” is composed of three hydraulic control valves (each with a solenoid valve and 
flow control valve), two buffer chambers, two hydraulic pumps, and an ABS motor. The hydraulic unit 
adjusts the front and rear wheel brake fluid pressure  to control the wheel speed according to signals 
transmitted from the ABS ECU.
 Hydraulic control valve
The hydraulic control valve is composed of a flow control valve and solenoid valve.
When the ABS is activated, the flow control valve regulates the flow of brake fluid to the brake and 
the solenoid valve decreases and in creases the brake fluid pressure.
1.When the brakes are operated normally, the solenoid  valve “2” is closed, the spool “3” of the flow 
control valve does not move, and the hydraulic line between the brake master cylinder and brake 
caliper is open.
2.When the ABS is activated, the solenoid valve “2 ” is opened by the power supplied from the ABS 
ECU signals to decrease the brake fluid pressure  and the spool “3” of the flow control valve is 
moved toward the solenoid valve.
3.When the ABS ECU stops transmitting  signals to decrease the brake fluid pressure, the solenoid 
valve “2” closes and the brake fluid is pressuriz ed again. Pressurizing the brake fluid again, while 
the ABS is activated, limits the flow of the brake  fluid with the movement of the flow control valve 
spool “3” and provides a gradual pressure increase.
1. To the rear brake master cylinder
2. Hydraulic pump
3. ABS motor
4. Buffer chamber
5. Hydraulic control valve 6. To the front brake master cylinder
7. To the rear brake caliper
8. To the ABS ECU
9. To the front brake caliper 
						

							
FEATURES
1-16
 Buffer chamberThe buffer chamber accumulates the brake fluid  that is depressurized while the ABS is operating.
1. Orifice
2. Solenoid valve 3. Spool
4. Flow control valve
1. Buffer chamber (pressurized)
2. Buffer chamber (depressurized)
3. Raised piston 
						

							
FEATURES
1-17
ABS ECU (electronic control unit)
The ABS ECU “1” controls the ABS and is installed under the fuel tank. To protect the ABS ECU 
from water damage, it is protected by a cover “2”.
As shown in the block following diagram, the ABS ECU receives wheel sensor signals from the front 
and rear wheels and also receives si gnals from other monitor circuits.
1. Battery
2. Engine stop switch
3. Starting circuit cut-off relay
4. Sidestand switch
5. Starter relay
6. Starter motor 7. Start switch
8. Front wheel sensor
9. Rear wheel sensor
10.Main fuse
11.Main switch
12.Generator 
						

							
FEATURES
1-18
The necessary actions are confirmed using the monitor circuit and control signals are transmitted to 
the hydraulic unit and ABS motor relay.
ABS control operation
The ABS control operation performed in the ABS  ECU is divided into the following two parts.
 Hydraulic control
 Self-diagnosis
These operations are performed once every 8/1000th of a second. When a failure is detected in the 
ABS, a malfunction code is stored  in the memory of the ABS ECU for easy problem identification 
and troubleshooting.
NOTE:
Some types of failures are not re corded in the memory of the ABS ECU (e.g., a drop in battery volt-
age).
ABS motor relay
The ABS motor relay “1” controls the power supply of  the hydraulic unit and is located on the battery.
13.Rectifier/regulator
14.ABS fuse
15.ABS motor fuse
16.ABS test coupler
17.ABS ECU
18.Rear brake light switch
19.Front brake light switch
20.Tail/brake light
21.Meter assembly 22.ABS warning light
23.ABS motor relay
24.Signal fuse
25.Ignition fuse
26.Hydraulic unit
27.ABS motor
28.Front brake solenoid
29.Rear brake solenoid
1. Software operation flow
2. Main switch “ON”
3. Initialize
4. Self-diagnosis (when static)
5. Self-diagnosis (when riding)
6. Receive signals
7. Control operation
8. Depressurize/pressurize
A. 8/1000th of a second 
						

							
FEATURES
1-19
Composition and operation
The ABS motor relay is activated by signals transmitted from the ABS ECU and operates simulta-
neously when the ABS starts to reduc e the hydraulic pressure of the brake fluid. If the solenoid relay 
is turned off, the ABS motor relay is also deactivated and the motor stops operating if there is a mal-
function.
EAS4S81009
ABS OPERATION
The ABS hydraulic circuit consists of two system s: 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 “11” of the  solenoid valve is closed because a control signal 
has not been transmitted from t he ABS ECU and port A “7” and port B “9” of the flow control valve 
are open.
1. ABS motor relay
2. Solenoid valves
3. ABS ECU
4. Pump motor relay coil
5. Pump motor monitor
6. ABS warning light 7. Front brake solenoid
8. Rear brake solenoid
9. Hydraulic unit
10.Power supply
11.Power of solenoid
12.Power 
						

							
FEATURES
1-20
Therefore, when the brake lever is squeezed, the hydraulic pressure in the brake master cylinder 
increases and the brake fluid is sent to the brake caliper via port A “7” and port B “9”.
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 pr essurizes 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 “7” and port B “9”.
1. Brake master cylinder
2. Brake light switch
3. ABS motor
4. Hydraulic pump
5. Buffer chamber
6. Flow control valve
7. Port A
8. Spool 9. Port B
10.Orifice
11.Port D
12.Solenoid valve
13.Port C
14.Brake caliper
15.ABS ECU
16.ABS warning light 
						

							
FEATURES
1-21
Emergency braking (ABS activated)
1.Depressurized stateWhen the front wheel is about to lockup, port D “11” of the solenoid valve is opened by the 
“depressurization” signal transmitted from the ABS  ECU. When this occurs, the spool of the flow 
control valve compresses the return spring and closes port B “9”. Brake fluid that has entered 
through port A “7” is restricted by the orifice “10” and the brake fluid is sent to the brake caliper via 
port C “13” and port D “11”, and the buffer chamber. As a result, the hydraulic pressure in the 
brake caliper is reduced.
The brake fluid stored in the buffer chamber is pumped back to the brake master cylinder by the 
fluid pressure pump linked to the pump motor.
17.Brake fluid pressure
18.Time
19.Repressurizing