Yamaha Fz1n Service Manual

							
FUEL INJECTION SYSTEM
8-37
EAS27350
ECU SELF-DIAGNOSTIC FUNCTION
The ECU is equipped with a self-diagnostic function in order to ensure that the fuel injection system 
is operating normally. If this function detects a malfunction in the system, it immediately operates the 
engine under substitute characteristics and illuminat es the engine trouble warning light to alert the 
rider that a malfunction has occurred in the syst em. Once a malfunction has been detected, a fault 
code is stored in the memory of the ECU.
 To inform the rider that the fuel injection system  is not functioning, the engine trouble warning light 
flashes when the start switch is being pushed to start the engine.
 If a malfunction is detected in the system by  the self-diagnostic function, the ECU provides an 
appropriate substitute characteristic operation, and  alerts the rider of the detected malfunction by 
illuminating the engine trouble warning light.
 After the engine has been stopped, the lowest fault code number appears on the odometer/tripme-
ter/fuel reserve tripmeter LCD. Once a fault code has been displayed, it remains stored in the 
memory of the ECU until it is deleted.
Engine trouble warning light indication and FI system operation
* The warning light flashes when any one of the c onditions listed below is present and the start
switch is pushed:
Checking the engine trouble warning light
The engine trouble warning light comes on for 1.4 seconds after the main switch has been turned to 
“ON” and it comes on while the start switch is being pushed. If the warning light does not come on 
under these conditions, the warning light (LED) may be defective. Warning light  indica-
tion ECU operation FI operation Vehicle operation
Flashing* Warning provided  when unable to start 
engineOperation stopped Cannot be operated
Remains on Malfunction detected Operated with substi- tute characteristics in 
accordance with the 
description of the mal-
functionCan or cannot be oper-
ated depending on the 
fault code
11: Cylinder identification  sensor 30: Lean angle sensor
(latch up detected)
12: Crankshaft position sensor 41: Lean angle sensor (open or short-circuit)
19: Sidestand switch (open circuit in the wire to the ECU) 50: ECU internal malfunction
(faulty ECU memory) 
						

							
FUEL INJECTION SYSTEM
8-38
ET2D1027
SELF-DIAGNOSTIC FUNCTION TABLE
If the ECU detects an abnormal signal from a sensor while the vehicle is being driven, the ECU illu-
minates the engine trouble warning light and provides the engine with alternate operating instruc-
tions that are appropriate for the type of malfunction.
When an abnormal signal is received from a sensor, the ECU processes the specified values that 
are programmed for each sensor in order to provide the engine with alternate operating instructions 
that enable the engine to continue to operate or stop operating, depending on the conditions.
Self-Diagnostic Function table
a. Main switch “OFF”
b. Main switch “ON”
c. Engine trouble warning light off
d. Engine trouble warning light on for 1.4 sec- onds
Fault 
code No. Item Symptom Able/
unable 
to start Able/
unable 
to drive
11 Cylinder  identifica-
tion sensor
No normal signals are received from the 
cylinder identificati
on sensor when the 
engine is started or while the vehicle is 
being driven. Unable Able
12 Crankshaft position 
sensor No normal signals are received from the 
crankshaft position sensor.
Unable Unable
13 Intake air pressure 
sensor
(open or short circuit) Intake air pressure sensor:
open or short circuit detected. Able Able
14 Intake air pressure 
sensor hose line
(piping system) Intake air pressure sensor:
faulty intake air pressure sensor system. Able Able
15 Throttle position sen-
sor
(open or short circuit) Throttle position sensor:
open or short circuit detected. Able Able
16 Throttle position sen-
sor
(stuck) Throttle position sensor is stuck.
Able Able
17 EXUP servo motor 
potention circuit
(open or short circuit) EXUP servo motor potension circuit:
open or short circuit detected. Able Able
18 EXUP servo motor 
(stuck) EXUP servo motor is stuck.
Able Able
19 Sidestand switch 
(open circuit in the 
wire to the ECU) Open circuit in the input line of ECU No.24 
terminal is detected when start switch is 
pressed from the sidestand switch to the 
ECU.
Unable Unable
20 Intake air pressure 
sensor or atmo-
spheric pressure sen-
sor When the main switch is turned to “ON”, 
the atmospheric pressure sensor voltage 
and intake air pressure sensor voltage dif-
fer greatly.
Able Able 
						

							
FUEL INJECTION SYSTEM
8-39
21Coolant temperature 
sensor
(open or short circuit) Coolant temperature sensor:
open or short circuit detected. Able Able
22 Intake air temperature 
sensor
(open or short circuit) Intake air temperature sensor:
open or short circuit detected. Able Able
23 Atmospheric pressure 
sensor
(open or short circuit) Atmospheric pressure sensor:
open or short circuit detected. Able Able
24 O
2 sensor No normal signal is received from the O2 
sensor. Able Able
30 Lean angle sensor 
(latch up detected) No normal signal is received from the lean 
angle sensor.
Unable Unable
33 Cylinder-#1 ignition 
coil
(open circuit)
Primary lead of the cylinder-#1 ignition 
coil:
open circuit detected. Able 
(depend- ing on 
the num- ber of faulty 
cylin- ders) Able 
(depend- ing on 
the num- ber of faulty 
cylin- ders)
34 Cylinder-#2 ignition 
coil
(open circuit)
Primary lead of the cylinder-#2 ignition 
coil:
open circuit detected. Able 
(depend-
ing on 
the num- ber of 
faulty cylin- ders) Able 
(depend-
ing on 
the num- ber of 
faulty cylin- ders)
35 Cylinder-#3 ignition 
coil
(open circuit)
Primary lead of the cylinder-#3 ignition 
coil:
open circuit detected. Able 
(depend-
ing on 
the num- ber of 
faulty cylin- ders) Able 
(depend-
ing on 
the num- ber of 
faulty cylin- ders)
36 Cylinder-#4 ignition 
coil
(open circuit)
Primary lead of the cylinder-#4 ignition 
coil:
open circuit detected. Able 
(depend- ing on 
the num-
ber of faulty cylin-
ders) Able 
(depend- ing on 
the num-
ber of faulty cylin-
ders)
Fault 
code No.
Item Symptom Able/
unable 
to start Able/
unable 
to drive 
						

							
FUEL INJECTION SYSTEM
8-40
Communication error with the meter39
Injector
(open circuit)
Injector:
open circuit detected. Able 
(depend- ing on 
the num- ber of faulty 
cylin- ders) Able 
(depend- ing on 
the num- ber of faulty 
cylin- ders)
41 Lean angle sensor
(open or short-circuit) Lean angle sensor:
open or short circuit detected.
Unable Unable
42 Speed sensor No normal signals are received from the 
speed sensor. Able Able
Neutral switch Neutral switch:
open or short circuit detected.
43 Fuel system voltage 
(monitoring voltage) Power supply to the injectors and the fuel 
pump is not normal.
Able Able
44 Error in writing the 
amount of CO adjust-
ment on EEPROM An error is detected while reading or writ-
ing on EEPROM (CO adjustment value). Able Able
46 Vehicle system power 
supply
(monitoring voltage) Power supply to the fuel injection system 
is not normal. Able Able
47 Sub-throttle servo 
motor potention (open 
or short circuit) sub-throttle servo motor potention:open or 
short circuit detected.
Able Able
48 Sub-throttle servo 
motor (lock) A lock of the sub-throttle servo motor is 
detected.
Able Able
50 ECU internal malfunc-
tion
(memory check error) ECU memory is faulty. (When this mal-
function is detected in the ECU, the fault 
code number might not appear on the 
meter.)
Unable Unable
– Start unable warning Relay is not turned ON even if the crank 
signal is input while the start switch is 
turned ON.
When the start switch is turned ON while 
an error is detected with the fault code of 
No.11, 12, 19, 30, 41 or 50. Unable Unable
Fault 
code No. Item Symptom Able/
unable 
to start Able/
unable 
to drive
Er-1 ECU internal malfunc-
tion
(output signal error) No signals are received from the ECU.
Unable Unable
Fault 
code No. Item Symptom Able/
unable 
to start Able/
unable 
to drive 
						

							
FUEL INJECTION SYSTEM
8-41
EAS27400
TROUBLESHOOTING METHOD
The engine operation is not normal and the
engine trouble warning light comes on.
1. Check: Fault code number
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Check the fault code number displayed on  the meter.
b. Identify the faulty system with the fault 
code. Refer to “Self-Diagnostic Function 
table”.
c. Identify the probable cause of malfunction.  Refer to “Diagnostic code table”.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
2. Checking and repair the probable cause of 
malfunction.
3. Perform ECU reinstatement action. Refer to “Reinstatement method” of table in 
“TROUBLESHOOTING DETAILS”.
4. Turn the main switch to “OFF” and back to  “ON”, then check that no fault code number 
is displayed.
NOTE:
If fault codes are displayed, repeat steps (1) to 
(4) until no fault code number is displayed.
5. Erase the malfunction history in the diag-
nostic mode. Refer to “Sensor operation 
table (Diagnostic code No.62)”.
NOTE:
Turning the main switch to “OFF” will not erase 
the malfunction history.
The engine operation is not normal but the
engine trouble warning light does not come
on.
1. Check the operation of following sensors and actuators in the Diagnostic mode. 
Refer to “Sensor operation table” and 
“Actuator operation table”.
Er-2
ECU internal malfunc-
tion
(output signal error) No signals are received from the ECU 
within the specified duration. Unable Unable
Er-3 ECU internal malfunc-
tion
(output signal error) Data from the ECU cannot be received 
correctly. Unable Unable
Er-4 ECU internal malfunc-
tion
(input signal error) Non-registered data has been received 
from the meter. Unable Unable
Fault 
code No. Item Symptom Able/
unable 
to start Able/
unable 
to drive
Fault code No. Fault code No.
Check and repair. 
Refer to TROUBLE-
SHOOTING 
DETAILS on page 8-
50.
Monitor the operation 
of the sensors and 
actuators in the diag-
nostic mode. Refer to 
“Sensor operation 
table” and “Actuator 
operation table”. Check and repair.
Refer to Self-Diag-
nostic Function table.
01: Throttle position sensor (throttle angle)
02: Atmospheric pressure sensor
05: Intake air pressure sensor
06: Coolant temperature sensor
07: Vehicle speed pulse
09: Fuel system voltage (battery bolt)
21: Neutral switch
30: Ignition coil #1
31: Ignition coil #2
32: Ignition coil #3
33: Ignition coil #4
36: Injector #1
37: Injector #2
38: Injector #3
39: Injector #4
48: AI system solenoid
53: EXUP servo motor
56: Sub-throttle servo motor 
						

							
FUEL INJECTION SYSTEM
8-42
If a malfunction is detected in the sensors 
or actuators, repair or replace all faulty 
parts.If no malfunction is detected in the sensors 
and actuators, check and repair inner parts 
of the engine.
EAS27420
DIAGNOSTIC MODE
Setting the diagnostic mode
1. Turn the main switch to “OFF” and set the engine stop switch to “ ”.
2. Disconnect the wire harness coupler from the fuel pump.
3. Press and hold the “SELECT” and “RESET” buttons
, turn the main switch to “ON”, and continue 
to press the buttons for 8 seconds or more.
NOTE:
 All displays on the meter disappear except the odometer/tripmeter/fuel reserve tripmeter display.
 “dI” appears on the odometer/tripmeter/fuel reserve tripmeter LCD.
4. Press the “SELECT” button to select the diagnostic mode “dI”.
5. After selecting “dI”, simultaneously press the “SELECT” and “RESET” buttons for 2 seconds or  more to activate the diagnostic mode. The diagnostic code number “d01” appears on the clock 
LCD.
6. Set the engine stop switch to “ ”.
7. Select the diagnostic code number corresponding to the fault code number by pressing the  “SELECT” and “RESET” buttons.
NOTE:
 The diagnostic code number appears on the LCD meter (d01–70).
 To decrease the selected diagnostic code number , press the “RESET” button. Press the “RESET” 
button for 1 second or longer to automati cally decrease the diagnostic code numbers.
 To increase the selected diagnostic code number, press the “SELECT” button. Press the 
“SELECT” button for 1 second or longer to au tomatically increase the diagnostic code numbers.
8. Verify the operation of the sensor or actuator.  Sensor operation 
						

							
FUEL INJECTION SYSTEM
8-43
The data representing the operating conditions of the sensor appears on the odometer/tripme-
ter/fuel reserve tripmeter LCD.
 Actuator operation Set the engine stop switch to “ ” to operate the actuator.
NOTE:
If the engine stop switch is set to “ ”, set it to “ ”, and then set it to “ ” again.
9. Turn the main switch to “OFF” to cancel the diagnostic mode.
Fault code table
Fault code  No. Symptom Probable cause of malfunction
Diagnostic 
code No.
11  No normal signals are 
received from the cylin-
der identification sensor 
when the engine is 
started or while the vehi-
cle is being driven.  Open or short circuit in sub wire harness.
 Open or short circuit in wire harness.
 Defective cylinder id
entification sensor.
 Improperly installed sensor.
 Malfunction in ECU. —
12 No normal signals are 
received from the crank-
shaft position sensor.  Open or short circuit in wire harness.
 Defective crankshaft position sensor.
 Malfunction in pickup rotor.
 Improperly installed sensor.
 Malfunction in ECU. —
13 Intake air pressure sensor: 
open or short circuit 
detected.  Open or short circuit in wire harness.
 Open or short circuit in sub wire harness.
 Defective intake air pressure sensor.
 Malfunction in ECU.
03
14 Intake air pressure sensor: 
faulty intake air pressure 
sensor system.  Intake air pressure sensor hose is 
detached, clogged, kinked, or pinched.
 Malfunction in ECU. 03
15 Throttle position sensor: 
open or short circuit 
detected.  Open or short circuit in wire harness.
 Open or short circuit in sub wire harness.
 Defective throttle position sensor.
 Improperly installed throttle position sensor.
 Malfunction in ECU. 01
16 Throttle position sensor: 
stuck  Stuck throttle position sensor.
 Malfunction in ECU.
01
17 EXUP servo motor poten-
tion circuit: open or short 
circuit detected.  Open or short circuit in sub wire harness.
 Detective EXUP servo motor (potention cir-
cuit). 53
18 EXUP servo motor is stuck.  Open or 
short circuit in sub wire harness.
 Stuck EXUP servo motor (mechanism).
 Stuck EXUP servo motor (motor). 53
19 Open circuit is detected in 
the input line of ECU No.24 
terminal is detected when 
the start switch is pressed.  Open circuit in wire harness (ECU Coupler).
 Malfunction in ECU.
20 
						

							
FUEL INJECTION SYSTEM
8-44
20When the main switch is 
turned to “ON”, the atmo-
spheric pressure sensor 
voltage and intake air pres-
sure sensor voltage differ 
greatly.  Atmospheric pressure sensor hose is 
clogged.
 Intake air pressure sensor hose is clogged, 
kinked, or pinched.
 Malfunction of the atmospheric pressure  sensor in the intermediate electrical poten-
tial.
 Malfunction of the intake air pressure sen- sor in the intermediate electrical potential.
 Malfunction in ECU. 02
03
21 Coolant temperature sen-
sor: open or short circuit 
detected.  Open or short circuit in wire harness.
 Defective coolant temperature sensor.
 Improperly installed coolant temperature 
sensor.
 Malfunction in ECU. 06
22 Intake air temperature sen-
sor: open or short circuit 
detected.  Open or short circuit in wire harness.
 Defective intake air temperature sensor.
 Improperly installed intake air temperature 
sensor.
 Malfunction in ECU. 05
23 Atmospheric pressure sen-
sor: open or short circuit 
detected.  Open or short circuit in sub wire harness.
 Defective atmospheric pressure sensor.
 Improperly installed atmospheric pressure 
sensor.
 Malfunction in ECU. 02
24 No normal signal is 
received from the O
2 sen-
sor.  Open or short circuit in wire harness.
 Defective O2 sensor.
 Improperly installed O
2 sensor.
 Malfunction in ECU. —
30 No normal signal is 
received from the lean 
angle sensor.  Vehicle has overturned.
 Defective lean angle sensor.
 Improperly installed lean angle sensor.
 Malfunction in ECU.
08
33 Open circuit detected in the 
primary lead of the cylinder-
#1 ignition coil.  Open circuit in wire harness.
 Malfunction in ignition coil.
 Malfunction in a component of ignition cut-
off circuit system.
 Malfunction in ECU. 30
34 Open circuit detected in the 
primary lead of the cylinder-
#2 ignition coil.  Open circuit in wire harness.
 Malfunction in ignition coil.
 Malfunction in a component of ignition cut-
off circuit system.
 Malfunction in ECU. 31
35 Open circuit detected in the 
primary lead of the cylinder-
#3 ignition coil.  Open or short circuit in wire harness.
 Malfunction in ignition coil.
 Malfunction in a component of ignition cut-
off circuit system.
 Malfunction in ECU. 32
Fault 
code 
No. Symptom Probable cause of malfunction
Diagnostic 
code No. 
						

							
FUEL INJECTION SYSTEM
8-45
36Open circuit detected in the 
primary lead of the cylinder-
#4 ignition coil.  Open or short circuit in wire harness.
 Malfunction in ignition coil.
 Malfunction in a component of ignition cut-
off circuit system.
 Malfunction in ECU. 33
39 Open circuit detected in a 
injector.
 Open or short circuit sub-wire- harness.
 Open or short circuit in wire harness.
 Improperly installed injector.
 Defective injector. 36
37
38
39
41 Lean angle sensor: open or 
short circuit detected.  Open or short circuit in wire harness.
 Defective lean angle sensor.
 Malfunction in ECU. 08
42 No normal signals are 
recieved from the speed 
sensor.
 Open or short circuit in wire harness.
 Malfunction in speed sensor.
 Malfunction in ECU.
07
Neutral switch:
open or short circuit 
detected.  Open or short circuit in wire haraness.
 Malfunction in neutral switch.
 Malfunction in ECU.
21
43 Power supply to the injec-
tors and the fuel pump is 
not normal.  Open circuit in wire harness.
 Malfunction in ECU. 09
44 An error is detected while 
reading or writing on 
EEPROM (CO adjustment 
value).  Malfunction in ECU. (The CO adjustment 
value is not properly written on or read from 
the internal memory). 60
46 Power supply to the fuel 
injection system relay is not 
normal.  Malfunction in the charging system.
Refer to CHARGING SYSTEM on page 8-
11.
—
47 Sub-throttle servo motor 
potention circuit:
open or short circuit 
detected.  Open or short circuit in wire harness.
 Detective Sub-throttle servo motor (poten-
tion circuit). 56
48 Sub-throttle servo motor is 
stuck.
 Open or short circuit in wire harness.
 Stuck Sub-throttle servo motor (mecha-
nism).
 Stuck Sub-throttle servo motor (motor). 56
50 Faulty ECU memory. (When 
this malfunction is detected 
in the ECU, the fault code 
number might not appear 
on the meter.)  Malfunction in ECU. (The program and data 
are not properly written on or read from the 
internal memory.) —
Er-1 No signals are received 
from the ECU.
 Open or short circuit in wire harness.
 Malfunction in meter.
 Defective wire connection of the ECU cou-
pler.
 Malfunction in ECU. —
Fault 
code 
No. Symptom Probable cause of malfunction
Diagnostic 
code No. 
						

							
FUEL INJECTION SYSTEM
8-46
Sensor operation tableEr-2
No signals are received 
from the ECU within the 
specified duration.  Improper connection in wire harness.
 Malfunction in meter.
 Malfunction in ECU.
—
Er-3 Data from the ECU cannot 
be received correctly.  Improper connection in wire harness.
 Malfunction in meter.
 Malfunction in ECU. —
Er-4 Non-registered data has 
been received from the 
meter.  Improper connection in wire harness.
 Malfunction in meter.
 Malfunction in ECU.
—
Diag-
nostic  code 
No. Item Meter display Checking method
01 Throttle position sensor sig-
nal
 Fully closed position 15–18 Check with throttle valve 
fully closed.
 Fully opened position 95–100 Check with throttle valve  fully opened.
02 Atmospheric pressure Displays the atmospheric 
pressure. Compare the actually mea-
sured atmospheric pres-
sure with the meter display 
value.
03 Intake air pressure Displays the cylinder-#1 
intake air pressure. Set the engine stop switch 
to “ ” then operate the 
throttle while pushing the 
start switch “ ”. (If the dis-
play value changes, the 
performance is OK.)
05 Intake air temperature Displays the intake air tem-
perature. Compare the actually mea-
sured air temperature with 
the meter display value.
06 Coolant temperature Displays the coolant tempera-
ture. Compare the actually mea-
sured coolant temperature 
with the meter diaplay 
value.
07 Vehicle speed pulse 0–999 Check that the number 
increases when the rear 
wheel is rotated. The num-
ber is cumulative and does 
not reset each time the 
wheel is stopped.
08 Lean angle sensor Remove the lean angle 
sensor and incline it more 
than 65 degrees.
 Upright 0.4–1.4
 Overturned 3.7–4.4
Fault 
code 
No. Symptom Probable cause of malfunction
Diagnostic 
code No.