2008 NISSAN TIIDA Engine Control System

STC-4
< SERVICE INFORMATION >[EPS]
EPS SYSTEM
EPS SYSTEM
System DescriptionINFOID:0000000001703872
EPS CONTROL UNIT
• EPS control unit performs an arithmetical operation on data, such
as steering wheel turning force (sensor signal) from the torque
sensor, vehicle speed signal, etc. Then it generates an optimum
assist torque to the EPS motor according to the driving condition.
• EPS control unit decreases the output to EPS motor while
extremely using the power steering function (e.g., full steering) for
protecting EPS motor and EPS control unit (Protect overload sta-
tus). While activating protect overload status, the assist torque
gradually decreases, and the steering wheel turning force
becomes heavy. The normal assist torque reactivates by not steer-
ing.
• In case of an error in the electrical system, the fail-safe function
stops output signals to the EPS motor. Then the previous state is changed to the manual steering state.
• Self-diagnosis can be done with CONSULT-III.
EPS MOTOR
EPS motor provides the assist torque by control signal from EPS control unit.
TORQUE SENSOR
Torque sensor detects the steering torque, and transmit the signal to
EPS control unit.
REDUCTION GEAR
Reduction gear increases the assist torque provided from EPS motor with worm gears, and outputs to the col-
umn shaft.
EPS WARNING LAMP
Turns ON when there is a malfunction in EPS system. It indicates that fail-safe mode is engaged and enters a
manual steering state (Control turning force steering wheel becomes heavy).
Also turns ON when ignition switch is turned ON, for purpose of lamp check. Turns OFF after the engine starts
if system is normal.
EPS Warning Lamp Indication
SGIA1647E
SGIA1648E
Condition EPS warning lamp
Lamp checkTurns ON when ignition switch is turned ON.
Turns OFF after engine start.
EPS system malfunctionON
Other than above (system normal) OFF

EPS SYSTEM
STC-5
< SERVICE INFORMATION >[EPS]
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SchematicINFOID:0000000001703873
COMPONENTS FUNCTION DESCRIPTION
CAN CommunicationINFOID:0000000001703874
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN-H line, CAN-L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
For details, refer to LAN-23, "
CAN System Specification Chart".
WGIA0187E
Component parts Function
EPS control unit
(Electric power steering control unit)• Outputs optimum assist torque signal to EPS motor.
• Reduces output signals to EPS motor and protects EPS motor and EPS control unit when us-
ing power steering continuously and excessively.
• As a fail-safe function, turned off output signal to EPS motor and then enters a manual steer-
ing state, if malfunction is detected in EPS system.
EPS motor Products assist torque by control signal from EPS control unit.
Torque sensor Detects steering wheel turning force and outputs sensor signal to EPS control unit.
Reduction gear Increases motor-produced assist torque by worm gear and transmits it to column shaft.
EPS warning lamp Illuminates if malfunction is detected in electrical system of EPS system.
ECMTransmits the following signals via CAN communication to EPS control unit.
• Engine status signal
ABS actuator and electric unit (con-
trol unit) (With ABS)Transmits the following signals via CAN communication to EPS control unit.
• Vehicle speed signal
Combination meterTransmits the following signals via CAN communication to EPS control unit.
• Vehicle speed signal
TCM (Without ABS)Transmits the following signals via CAN communication to EPS control unit.
• Vehicle speed signal

STC-12
< SERVICE INFORMATION >[EPS]
TROUBLE DIAGNOSIS
CAUTION:
If “CAN COMM CIRCUIT [U1000]” is displayed with other DTCs, first perform the trouble diagnosis for CAN communication
line.
How to Erase Self-Diagnostic Results
1. Perform applicable inspection of malfunctioning item and then repair or replace.
2. Turn ignition switch “OFF” to erase memory.
3. Turn ignition switch “ON” and select “SELF-DIAG RESULTS” mode with CONSULT-III.
4. Touch “ERASE” on CONSULT-III screen to erase DTC memory.
CAUTION:
If memory cannot be erased, perform diagnosis.
DATA MONITOR
Display Item List
EPS CONTROL UNIT PART NUMBER
Display a part number of EPS control unit carried by a vehicle.
Item
(CONSULT-III screen terms)Diagnostic item is detected when.... Check item
BATTERY VOLT
[C1601]When the power supply malfunction supplied to EPS control unit is
detected.STC-14, "
DTC C1601
BATTERY VOLT"
TORQUE SENSOR
[C1604]When the torque sensor malfunction assembled in steering column
assembly is detected. STC-15, "DTC C1604
TORQUE SENSOR"
EPS MOTOR
[C1606]When the motor driver malfunction of EPS control unit or EPS motor
malfunction is detected.STC-16, "DTC C1606
EPS MOTOR"
EEPROM
[C1607]When the memory (EEPROM) system malfunction is detected in
EPS control unit.STC-17, "DTC C1607
EEPROM"
CONTROL UNIT
[C1608]When the internal malfunction is detected in EPS control unit.STC-17, "DTC C1608
CONTROL UNIT"
CAN VHCL SPEED
[C1609]When the malfunction is detected in vehicle speed signal received
with CAN communication.STC-18, "DTC C1609
CAN VHCL SPEED"
CAN ENG RPM
[C1610]When the malfunction is detected in engine status signal received
with CAN communication.STC-19, "DTC C1610
CAN ENG RPM"
CAN COMM CIRCUIT
[U1000]When EPS control unit is not transmitting or receiving CAN commu-
nication signal 2 seconds or more.STC-19, "DTC U1000
CAN COMM CIRCUIT"
NO DTC IS DETECTED.
FURTHER TESTING MAY BE RE-
QUIRED.No NG item has been detected. —
Monitor item (Unit) Remarks
MOTOR VOL (V) Power supply voltage for EPS control unit is displayed
TORQUE SENSOR (Nm) Steering wheel turning force detected by torque sensor is displayed
MOTOR SIG (A) Current commanded value to EPS motor is displayed
MOTOR CURRENT (A) Current value consumed by EPS motor is displayed
VEHICLE SPEED (km/h) or (mph) Vehicle speed is displayed from vehicle speed signal with CAN communication
WARNING LAMP (ON/OFF) EPS warning lamp control status is displayed
DERATING STAT (ON/OFF) Protect overload status is displayed
ENGINE STATUS (STOP/RUN) Engine speed is displayed from engine status signal with CAN communication

STC-14
< SERVICE INFORMATION >[EPS]
TROUBLE DIAGNOSIS FOR SYSTEM
TROUBLE DIAGNOSIS FOR SYSTEM
DTC C1601 BATTERY VOLTINFOID:0000000001703883
CONSULT-III REFERENCE VALUE IN DATA MONITOR MODE
Data are reference value.
TERMINALS AND REFERENCE VALUES FOR EPS CONTROL UNIT
Refer to STC-10, "EPS Terminal and Reference Value".
DIAGNOSTIC PROCEDURE
1.CHECK EPS CONTROL UNIT POWER SUPPLY CIRCUIT
1. Turn ignition switch “OFF”.
2. Disconnect EPS control unit harness connector.
3. Turn ignition switch “ON”. (Do not start engine.)
4. Check voltage between EPS control unit harness connector (A)
terminals and ground.
5. Turn ignition switch “OFF”.
6. Check voltage between EPS control unit harness connector (A)
terminals and ground.
7. Connect EPS control unit harness connector.
OK or NG
OK >> GO TO 2.
NG >> Check the following. If any items are damaged, repair or replace damaged parts.
• 60 A fusible link (No. m, located in the fuse and fusible link block). Refer to PG-3
.
• 10 A fuse [No. 2, located in the fuse block (J/B)]. Refer to PG-3
.
• Harness for short or open between battery and EPS control unit harness connector M54 termi-
nal 17.
• Harness for short or open between ignition switch and EPS control unit harness connector M53
terminal 10.
2.CHECK EPS CONTROL UNIT GROUND CIRCUIT
1. Turn ignition switch “OFF”.
2. Disconnect EPS control unit harness connector.
Monitor item (Unit) Content Condition Display value
MOTOR VOL (V) Power supply voltage for EPS control unit Ignition switch: ON Battery voltage
Connector Terminal Voltage
M53 10 – Ground Battery voltage
M54 17 – Ground Battery voltage
SGIA1626E
Connector Terminal Voltage
M53 10 – Ground Approx. 0 V
M54 17 – Ground Battery voltage
SGIA1627E

TROUBLE DIAGNOSIS FOR SYSTEM
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< SERVICE INFORMATION >[EPS]
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3. Check continuity between EPS control unit harness connector
(A) terminal and ground.
Also check harness for short to power.
4. Connect EPS control unit harness connector.
OK or NG
OK >> GO TO 3.
NG >> Repair open circuit or short to ground or short to power
in harness or connectors.
3.CHECK DTC
Start engine.
Does EPS warning lamp turn OFF?
YES >>INSPECTION END
NO >> Perform self-diagnosis, repair or replace damaged parts. Refer to STC-11, "
CONSULT-III Func-
tion (EPS)".
DTC C1604 TORQUE SENSORINFOID:0000000001703884
CONSULT-III REFERENCE VALUE IN DATA MONITOR MODE
Data are reference value.
*: In the front of the value, “L” is displayed at steering left and “R” is displayed at steering right.
TERMINALS AND REFERENCE VALUES FOR EPS CONTROL UNIT
Refer to STC-10, "EPS Terminal and Reference Value".
DIAGNOSTIC PROCEDURE
1.CHECK TORQUE SENSOR SIGNAL
With CONSULT-III
1. Start engine.
2. Select “DATA MONITOR” mode for “EPS” with CONSULT-III.
3. Check the value of “TORQUE SENSOR”. Refer to STC-9, "
EPS Control Unit Input/Output Signal Refer-
ence Value".
Without CONSULT-III1. Start engine.
2. Check voltage between EPS control unit harness connector M53 terminals 4, 5, 6, 7 and ground. Refer to
STC-10, "
EPS Terminal and Reference Value".
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK HARNESS AND CONNECTOR
1. Turn ignition switch “OFF”.
2. Disconnect EPS control unit harness connector and torque sensor harness connector.
Connector Terminal Continuity
M54 18 Yes
SGIA1628E
Monitor item (Unit) Content Condition Display value
TORQUE SENSOR (Nm) Steering wheel turning force Engine runningSteering wheel: Not steering
(There is no steering force)0.00 Nm
Steering wheel: Steering0 – 8.19 Nm*
(The value is changed
according to steering
left or right)

STC-16
< SERVICE INFORMATION >[EPS]
TROUBLE DIAGNOSIS FOR SYSTEM
3. Check continuity between EPS control unit harness connector
(A) M53 terminals 4, 5, 6, 7 and torque sensor harness connec-
tor (B) M63 terminals 1, 2, 3, 4.
Also check harness for short to ground and short to power.
4. Connect EPS control unit harness connector and torque sensor harness connector.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3.CHECK EPS CONTROL UNIT
Check EPS control unit input/output signal. Refer to STC-9, "
EPS Control Unit Input/Output Signal Reference
Va l u e".
OK or NG
OK >> GO TO 4.
NG >> Check EPS control unit pin terminals for damage or loose connection with harness connector. If
any items are damaged, repair or replace damaged parts.
4.CHECK DTC
Perform the self-diagnosis, after driving the vehicle for a while.
OK or NG
OK >>INSPECTION END
NG >> Torque sensor is malfunctioning. Replace steering column assembly. Refer to PS-9, "
Removal
and Installation".
DTC C1606 EPS MOTORINFOID:0000000001703885
CONSULT-III REFERENCE VALUE IN DATA MONITOR MODE
Data are reference value.
* : Almost in accordance with the value of “MOTOR SIG”. It is not a malfunction though these values are not accorded when steering
quickly.
TERMINALS AND REFERENCE VALUES FOR EPS CONTROL UNIT
Refer to STC-10, "EPS Terminal and Reference Value".
DIAGNOSTIC PROCEDURE
1.CHECK EPS MOTOR SIGNAL
Terminal Continuity
4 – 3
Ye s 5 – 2
6 – 1
7 – 4
SGIA1629E
Monitor item (Unit) Content Condition Display value
MOTOR SIG (A)Command current to EPS
motorEngine runningSteering wheel: Not steering
(There is no steering force)0.00 A
Steering wheel: Steering0 – 65.00 A
(The value is changed
according to steering left
or right)
MOTOR CURRENT (A)Consumption current of
EPS motorEngine runningSteering wheel: Not steering
(There is no steering force)0.00 A
Steering wheel: Steering0 – 65.00 A*
(The value is changed
according to steering left
or right)

TROUBLE DIAGNOSIS FOR SYSTEM
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< SERVICE INFORMATION >[EPS]
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With CONSULT-III
1. Start engine.
2. Select “DATA MONITOR” mode for “EPS” with CONSULT-III.
3. Check the values of “MOTOR SIG” and “MOTOR CURRENT”. Refer to STC-9, "
EPS Control Unit Input/
Output Signal Reference Value".
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK EPS MOTOR
1. Turn ignition switch “OFF”.
2. Disconnect EPS control unit harness connector.
3. Check resistance between EPS control unit harness connector
(A) terminals.
4. Connect EPS control unit harness connector.
OK or NG
OK >> GO TO 3.
NG >> EPS motor is malfunctioning. Replace steering column
assembly. Refer to PS-9, "
Removal and Installation".
3.CHECK EPS CONTROL UNIT
Check EPS control unit input/output signal. Refer to STC-9, "
EPS Control Unit Input/Output Signal Reference
Va l u e".
OK or NG
OK >> GO TO 4.
NG >> Check EPS control unit pin terminals for damage or loose connection with harness connector. If
any items are damaged, repair or replace damaged parts.
4.CHECK DTC
Perform the self-diagnosis, after driving the vehicle for a while.
OK or NG
OK >>INSPECTION END
NG >> GO TO 3.
DTC C1607 EEPROMINFOID:0000000001703886
DIAGNOSTIC PROCEDURE
1.PERFORM SELF-DIAGNOSIS
With CONSULT-III
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “SELF-DIAG RESULTS” mode for “EPS” with CONSULT-III.
3. Touch “ERASE”.
4. Turn ignition switch “OFF”, and wait at least 10 seconds.
5. Start engine.
6. Perform the self-diagnosis again.
Is the
“EEPROM [C1607]” displayed?
YES >> Replace EPS control unit. Refer to PS-9, "Removal and Installation".
NO >>INSPECTION END
DTC C1608 CONTROL UNITINFOID:0000000001703887
DIAGNOSTIC PROCEDURE
Connector Terminal Resistance
M60 19 – 20 Approx. 0.1 Ω or less
SGIA1630E

STC-18
< SERVICE INFORMATION >[EPS]
TROUBLE DIAGNOSIS FOR SYSTEM
1.PERFORM SELF-DIAGNOSIS
With CONSULT-III
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “SELF-DIAG RESULTS” mode for “EPS” with CONSULT-III.
3. Touch “ERASE”.
4. Turn ignition switch “OFF”, and wait at least 10 seconds.
5. Start engine.
6. Perform the self-diagnosis again.
Is the
“CONTROL UNIT [C1608]” displayed?
YES >> Replace EPS control unit. Refer to PS-9, "Removal and Installation".
NO >>INSPECTION END
DTC C1609 CAN VHCL SPEEDINFOID:0000000001703888
CONSULT-III REFERENCE VALUE IN DATA MONITOR MODE
Data are reference value.
* : It is not a malfunction, though it might not be corresponding just after ignition switch is turned ON.
DIAGNOSTIC PROCEDURE
1.CHECK DTC WITH COMBINATION METER
Perform self-diagnosis with combination meter. Refer to DI-13, "
CONSULT-III Function (METER/M&A)" .
Is any malfunction detected by self-diagnosis?
YES >> Check the malfunctioning system.
NO-1 >> With ABS: GO TO 2.
NO-2 >> Without ABS: GO TO 3.
2.CHECK DTC WITH ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)
Perform self-diagnosis with ABS actuator and electric unit (control unit). Refer to BRC-18, "
CONSULT-III
Function (ABS)" .
Is any malfunction detected by self-diagnosis?
YES >> Check the malfunctioning system.
NO >> GO TO 4.
3.CHECK DTC WITH TRANSMISSON CONTROL MODULE (TCM)
Perform self-diagnosis with TCM. Refer to AT-73, "
CONSULT-III Function (A/T)" .
Is any malfunction detected by self-diagnosis?
YES >> Check the malfunctioning system.
NO >> GO TO 4.
4.CHECK EPS CONTROL UNIT
Check EPS control unit input/output signal. Refer to STC-9, "
EPS Control Unit Input/Output Signal Reference
Va l u e" .
OK or NG
OK >> GO TO 5.
NG >> Check EPS control unit pin terminals for damage or loose connection with harness connector. If
any items are damaged, repair or replace damaged parts.
5.CHECK DTC
Perform the self-diagnosis, after driving the vehicle for a while.
OK or NG
Monitor item (Unit) Content Condition Display value
VEHICLE SPEED (km/h) or (mph) Vehicle speedVehicle stopped 0 km/h (0 mph)
While drivingApproximately equal to the indication on speed-
ometer (Inside of ±10%)