NISSAN LATIO 2010 Service Repair Manual

EPS SYSTEMSTC-5
< SYSTEM DESCRIPTION > [EPS]
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SYSTEM DESCRIPTION
EPS SYSTEM
System DiagramINFOID:0000000005600156
System DescriptionINFOID:0000000005600157
• 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 signal
to the EPS motor according to the driving condition.
• EPS control unit decreases the output signal to EPS mo tor while extremely using the power steering func-
tion (e.g., full steering) consecutively for protec ting EPS motor and EPS control unit (Overload protection
control). While activating overload protection control, the assist torque gradually decreases, and the steering
wheel turning force becomes heavy. The normal assist torque reactivates by no steering.
• 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 control unit will decrease assistance under the following 2 conditions.
- Extensive steering at low speed will cause the ECU and MOTOR to heat up, once temperature reaches crit-
ical point ECU will reduce current to reduce heat up. System will recover as temperature lowers (reduced or
no assistance).
- Holding steering on rack-end (full lock) for 1 second will cause the system to engage rack-end protection. This reduces assistance down to 50% in order to prevent heat up. Assistance is immediately returned to
100% when steering released or turned away from rack-end.
- Communicates the signal from each control unit via CAN communication.
WGIA0187E
Control unit Signal status
ECM Transmits mainly the follow
ing signals to EPS control uni t via CAN communication.
Engine status signal
ABS actuator and electric unit
(control unit) Transmits mainly the follow
ing signals to EPS control uni t via CAN communication.
Vehicle speed signal
Revision: January 20102010 Versa

STC-6
< SYSTEM DESCRIPTION >[EPS]
EPS SYSTEM
Component Parts Location
INFOID:0000000005600158
Component DescriptionINFOID:0000000005600159
Combination meter • Transmits mainly the following signals to EPS control unit via CAN communication.
Vehicle speed signal
• EPS warning lamp si gnal is received from the EPS co ntrol unit via CAN communication.
TCM (Without ABS) Transmits the following si
gnals via CAN communicatio n to EPS control until.
Engine status signal
• Vehicle speed signal
Control unit
Signal status
SGIA1623E
Components parts Reference
EPS control unit STC-15, "
Description"
EPS motorSTC-13, "Description"
Torque sensor STC-11, "Description"
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EPS SYSTEMSTC-7
< SYSTEM DESCRIPTION > [EPS]
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Reduction gear Reduction gear increa
ses the assist torque provided from EPS
motor with worm gears, and outputs to the column shaft.
EPS warning lamp STC-19, "
Description"
Components partsReference
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STC-8
< SYSTEM DESCRIPTION >[EPS]
DIAGNOSIS SYSTEM (EPS CONTROL UNIT)
DIAGNOSIS SYSTEM
(EPS CONTROL UNIT)
CONSULT-III FunctionINFOID:0000000005600160
FUNCTION
CONSULT-III can display each diagnostic item us ing the diagnostic test modes shown following.
ECU IDENTIFICATION
Displays the part number stored in the control unit.
SELF-DIAG RESULTS MODE
Display Item List
Refer to STC-24, "DTC Index".
CAUTION:
If “CAN COMM CIRCUIT [U1000]” is disp layed with other DTCs, first perform the trouble diagnosis for
CAN communication line.
DATA MONITOR MODE
Display Item List
*1: Almost in accordance with the value of MOTOR SIG. It is not a malfunction though these values are not accorded when steerin g
quickly.
*2: It is not a malfunction, though it might not be corresponding just after ignition switch in turned ON. Diagnostic test mode
Function
ECU identification Steering column assembly number can be read.
Self diagnostic result Self-diagnostic results can be read and erased quickly.
Data monitor Input/Output data in the EPS control unit can be read.
Monitor item (Unit) Remarks
MOTOR VOL (V) Displays the power supply voltage for EPS control unit.
TORQUE SENSOR (Nm) Displays steering wheel turning force detected by torque sensor.
MOTOR CURRENT (A) Displays the current value consumed by EPS motor.
MOTOR SIG (A)
*1Displays the current commanded value to EPS motor.
DERATING STAT (ON/OFF%) Protect overload status is displayed.
VEHICLE SPEED (km/h) or (MPH)
*2Vehicle speed is displayed from vehicle speed signal via CAN communication.
WARNING LAMP (On/Off) EPS warning lamp control status is displayed.
ENGINE STATUS (Stop/Run) Engine speed is displayed from engine status signal via CAN communication.
Revision: January 20102010 Versa

C1601 BATTERY POWER SUPPLYSTC-9
< DTC/CIRCUIT DIAGNOSIS > [EPS]
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DTC/CIRCUIT DIAGNOSIS
C1601 BATTERY POWER SUPPLY
DescriptionINFOID:0000000005600161
Power is supplied from the battery to EPS control unit.
DTC LogicINFOID:0000000005600162
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC REPRODUCTION PROCEDURE
With CONSULT-III
1. Turn the ignition switch OFF to ON.
2. Perform EPS control unit self-diagnosis.
Is DTC
“C1601” detected?
YES >> Proceed to diagnosis procedure. Refer to STC-9, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000005600163
1.CHECK EPS CONTROL UNIT GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect EPS control unit harness connector.
3. Check continuity between EPS control unit harness connector terminal and ground.
4. Connect EPS control unit harness connector.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repair open circuit or short to ground or short to power in harness or connectors.
2.CHECK EPS CONTROL UNI T POWER SUPPLY CIRCUIT
1. Check voltage between EPS control unit harness connector terminals and ground.
2. Turn ignition switch ON. CAUTION:
Never start the engine.
3. Check voltage between EPS control unit harness connector terminals and ground.
DTC Display item Malfunction detected condition Possible cause
C1601 BATTERY VOLT When a power supp
ly voltage to the EPS control unit
is maintained at or above 17.5 V or less than 9 V con-
tinuously for more than five seconds. • Harness or connector
• EPS control unit
EPS control unit
—Con tin uit y
Connector Terminal
M54 18Ground Existed
EPS control unit
—Volt a g e
Connector Terminal
M53 10
Ground Approx. 0 V
M54 17 Battery voltage
Revision: January 20102010 Versa

STC-10
< DTC/CIRCUIT DIAGNOSIS >[EPS]
C1601 BATTERY POWER SUPPLY
Is the inspection result normal?
YES >> GO TO 3.
NO >> Check the following. If any items are damaged, repair or replace damaged parts.
• 10A fuse (#2) open
- Harness for short between 10A fuse (#2) and pow er steering control unit harness connector No.
10 terminal.
• 60A fusible link (M) open
- Harness for short between 60A fusible link (M) and power steering control unit harness connec-
tor No. 10 terminal.
• Harness for open between ignition switch and power steering control unit harness connector No. 17 terminal.
• Harness for open between battery and power steering control unit harness connector No. 17 ter-
minal.
• Battery or ignition switch.
3.CHECK BATTERY VOLTAGE SIGNAL (1)
With CONSULT-III
1. Connect EPS control unit harness connector.
2. Start the engine. CAUTION:
Stop the vehicle.
3. Select “EPS”, “DATA MONITOR” and “MOTOR VO LT”, and perform the battery voltage inspection.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace EPS control unit. Refer to PS-9, "
Removal and Installation".
4.CHECK MOTOR VOLTAGE SIGNAL (2)
With CONSULT-III
Select “MOTOR VOLT” in “DATA MONITOR” of the EPS control unit. Check motor voltage with the steering
wheel fully turned leftward or rightward.
Is the value in
“DATA MONITOR”“between 9 V and 17.5 V”?
YES >> Check pin terminal and connection of each harness connector for damage or loose connection.
NO >> Check battery power supply and ignition power supply. Refer to STC-22, "
Wiring Diagram - ELEC-
TRONICALLY CONTROLLED POWER STEERING SYSTEM -".
EPS control unit
—Volt a ge
Connector Terminal
M53 10
Ground Battery voltage
M54 17
Monitor item ConditionDisplay value
MOTOR VOLT Engine runningBattery voltage
Revision: January 20102010 Versa

C1604 TORQUE SENSORSTC-11
< DTC/CIRCUIT DIAGNOSIS > [EPS]
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C1604 TORQUE SENSOR
DescriptionINFOID:0000000005600165
Torque sensor detects the steering torque, and transmit the signal to EPS control unit.
DTC LogicINFOID:0000000005600166
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC REPRODUCTION PROCEDURE
With CONSULT-III
1. Turn the ignition switch OFF to ON.
2. Perform EPS control unit self-diagnosis.
Is DTC
“C1604” detected?
YES >> Proceed to diagnosis procedure. Refer to STC-11, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000005600167
1.CHECK TORQUE SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF to ON. CAUTION:
Never start the engine.
2. Check voltage between EPS control unit harness connector terminals and ground. CAUTION:
Steering wheel is neutral position. (There is no steering force.)
Is the inspection result normal?
YES >> GO TO 2.
NO >> Perform the trouble diagnosis for battery power supply circuit. Refer to STC-9, "
Diagnosis Proce-
dure".
2.CHECK TORQUE SENSOR GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Check continuity between EPS control unit harness connector terminal and ground. CAUTION:
Steering wheel is neutral position. (There is no steering force.)
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair open circuit or short to ground or short to power in harness or connectors.
DTC Display item Malfunction detected condition Possible cause
C1604 TORQUE SENSOR When torque sensor output signal is malfunctioning. • Harness or connector
• Torque sensor
• EPS control unit
EPS control unit
—Volt a g e
Connector Terminal
M53 5Ground Approx. 5 V
EPS control unit
—Con tin uit y
Connector Terminal
M53 7Ground Yes
Revision: January 20102010 Versa

STC-12
< DTC/CIRCUIT DIAGNOSIS >[EPS]
C1604 TORQUE SENSOR
3.CHECK TORQUE SENSOR SIGNAL
1. Turn ignition switch ON.
2. Check voltage between EPS control unit harness connector terminal and ground. CAUTION:
Steering wheel is neutral position . (There is no steering force.)
Is the inspection result normal?
YES >> GO TO 4.
NO >> Torque sensor is malfunction. Replac e steering column assembly. Refer to PS-9, "
Removal and
Installation".
4.CHECK CONNECTOR
1. Turn ignition switch OFF.
2. Disconnect torque sensor harness connector.
3. Check terminal for deformation, disconnection, looseness, and so on. If any malfunction is found, repair or replace terminal.
Is the inspection result normal?
YES >> Replace EPS control unit. Refer to PS-9, "Removal and Installation".
NO >> Repair or replace error-detected parts.
EPS control unit —Volt a ge
Connector Terminal
M53 4
Ground Approx. 2.5V
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Revision: January 20102010 Versa

C1606 EPS MOTORSTC-13
< DTC/CIRCUIT DIAGNOSIS > [EPS]
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C1606 EPS MOTOR
DescriptionINFOID:0000000005600169
EPS motor provides the assist torque by the control signal from EPS control unit.
DTC LogicINFOID:0000000005600170
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.DTC REPRODUCTION PROCEDURE
With CONSULT-III
1. Turn the ignition switch OFF to ON.
2. Perform EPS control unit self-diagnosis.
Is DTC
“C1606” detected?
YES >> Proceed to diagnosis procedure. Refer to STC-13, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000005600171
1.CHECK EPS MOTOR
Check the EPS motor. Refer to STC-13, "
Component Inspection".
Is the inspection result normal?
YES >> GO TO 2.
NO >> EPS motor is malfunction. Replace steering column assembly. Refer to PS-9, "
Removal and
Installation".
2.CHECK CONNECTOR
1. Turn ignition switch OFF.
2. Disconnect EPS motor harness connector.
3. Check terminal for deformation, disconnection, looseness, and so on. If any malfunction is found, repair or replace terminal.
Is the inspection result normal?
YES >> Replace EPS control unit. Refer to PS-9, "Removal and Installation".
NO >> Repair or replace error-detected parts.
Component Inspection INFOID:0000000005600172
1.CHECK EPS MOTOR
1. Turn the ignition switch OFF.
2. Disconnect EPS motor harness connector.
3. Check resistance between EPS motor connector terminals.
Is the inspection result normal?
YES >> Inspection End
DTC Display item Malfunction detected condition Possible cause
C1606 EPS MOTOR When the motor driver malfunction of EPS control
unit or EPS motor malfunction is detected. • Harness or connector
• EPS motor
• EPS control unit
EPS motor
Resistance (Approx.)
Te r m i n a l
19 20 0.1 Ω or less
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STC-14
< DTC/CIRCUIT DIAGNOSIS >[EPS]
C1606 EPS MOTOR
NO >> EPS motor is malfunction. Replace steering column assembly. Refer to
PS-9, "Removal and
Installation".
Revision: January 20102010 Versa