wheel torque NISSAN LATIO 2011 Service Service Manual

EPS SYSTEMSTC-5
< SYSTEM DESCRIPTION > [EPS]
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SYSTEM DESCRIPTION
EPS SYSTEM
System DiagramINFOID:0000000005931224
System DescriptionINFOID:0000000005931225
• 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: May 2010 2011 Versa

STC-8
< SYSTEM DESCRIPTION >[EPS]
DIAGNOSIS SYSTEM (EPS CONTROL UNIT)
DIAGNOSIS SYSTEM
(EPS CONTROL UNIT)
CONSULT-III FunctionINFOID:0000000005931228
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.
CAN diag support MNTR The results of transmit/receive diagnosis of CAN communication can be read.
Data monitor Input/Output data in the EPS control unit can be read.
Monitor item (Unit) Remarks
BATTERY VOLT (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.
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: May 2010 2011 Versa

C1604 TORQUE SENSORSTC-11
< DTC/CIRCUIT DIAGNOSIS > [EPS]
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C1604 TORQUE SENSOR
DescriptionINFOID:0000000005931232
Torque sensor detects the steering torque, and transmit the signal to EPS control unit.
DTC LogicINFOID:0000000005931233
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:0000000005931234
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: May 2010 2011 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. Replace steering column assembly. Refer to PS-10, "
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-10, "Removal and Installation".
NO >> Repair or replace error-detected parts.
EPS control unit —Volt a ge
Connector Terminal
M53 4
Ground Approx. 2.5V
6
Revision: May 2010 2011 Versa

C1607, C1608 EPS CONTROL UNIT
STC-15
< DTC/CIRCUIT DIAGNOSIS > [EPS]
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C1607, C1608 EPS CONTROL UNIT
DescriptionINFOID:0000000005931239
EPS control unit performs an arithmetical operation on data, such as steering wheel turning force (sensor sig-
nal) from the torque sensor, vehicle speed signal, etc. T hen it generates an optimum assist torque signal to the
EPS motor according to the driving condition.
DTC LogicINFOID:0000000005931240
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
“C1607” or “C1608” detected?
YES >> Proceed to diagnosis procedure. Refer to STC-15, "Diagnosis Procedure".
NO >> Inspection End.
Diagnosis ProcedureINFOID:0000000005931241
1.PERFORM SELF-DIAGNOSIS
With CONSULT-III
1. Turn the ignition switch OFF to ON.
2. Erase EPS control unit self-diagnostic results.
3. Perform EPS control unit self-diagnosis.
Is DTC
“C1607” or “C1608” detected?
YES >> Replace EPS control unit. Refer to PS-10, "Removal and Installation".
NO >> Check EPS control unit pin terminals for damage or loose connection with harness connector. If
any item are damaged, repair or replace error-detected parts.
DTC Display item Malfunction detected condition Possible cause
C1607 EEPROM When the memory (EEPROM)
system malfunction is
detected in EPS control unit.
EPS control unit
C1608 CONTROL UNIT When the internal malfunction is detected in EPS
control unit.
Revision: May 2010
2011 Versa

STC-20
< ECU DIAGNOSIS INFORMATION >[EPS]
EPS CONTROL UNIT
ECU DIAGNOSIS INFORMATION
EPS CONTROL UNIT
Reference ValueINFOID:0000000005931254
VALUES ON THE DIAGNOSIS TOOL
CAUTION:
The output signal indicates the EPS control unit calculation data. Th
e normal values will be displayed
even in the event that the output circuit (harness) is open.
*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.
TERMINAL LAYOUT
PHYSICAL VALUES
Monitor item Display content Data monitor
Condition Display value
MOTOR VOL Power supply voltage for
EPS control unit Ignition switch: ON
Battery voltage
TORQUE SENSOR Steering wheel turning
force Engine runningSteering wheel: Not steering
(There is no steering force)
Approx. 0 Nm
Steering wheel: Right turn Positive value (Nm)
Steering wheel: Left turn Negative value (Nm)
MOTOR CURRENT Consumption current of
EPS motor Engine runningSteering wheel: Not steering
(There is no steering force)
Approx. 0 A
Steering wheel: Right or left
turn Displays consumption cur-
rent of EPS motor (A)
*1
MOTOR SIG
Command current to
EPS motor Engine runningSteering wheel: Not steering
(There is no steering force)
Approx. 0 A
Steering wheel: Right turn Negative value (A)
Steering wheel: Left turn Positive value (A)
DERATING STAT Displays overload sta-
tus.
Engine running
Off
VEHICLE SPEED Vehicle speed Vehicle stopped
0 km/h (0 mph)
While driving Approximately equal to the
indication on speedometer
(inside of
±10%)
*2
WARNING LAMP EPS warning lamp con-
dition EPS warning lamp: ON
On
EPS warning lamp: OFF Off
ENGINE STATUS Engine status Engine not running
Stop
Engine running Run
SGIA1624E
Revision: May 2010 2011 Versa

EPS CONTROL UNITSTC-21
< ECU DIAGNOSIS INFORMATION > [EPS]
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Te r m i n a l N o . (Wire Color) Description
ConditionVa l u e
(Approx.)
+ − Signal name Input/Output
4
(V) Ground Torque sensor sub Input Ignition switch: ON
Steering wheel: Not
steering (There is no
steering force) 2.5 V
Engine running Steering wheel: steer-
ing 1.6 V – 3.4 V
(The value is changed according to steering
left or right)
5
(BR −) Ground
Torque sensor power
supply Output
Ignition switch: ON 5 V
6
(− ) Ground Torque sensor main Input Ignition switch: ON
Steering wheel: Not
steering (There is no
steering force) 2.5 V
Engine running Steering wheel: steer-
ing 1.6 V – 3.4 V
(The value is changed according to steering
left or right)
7
(R) Ground Torque sensor ground —
Always0 V
9
(L) Ground CAN-H
Input/Output ——
10
(O) Ground Ignition power supply Input Ignition switch: ON
Battery voltage
Ignition switch: OFF 0 V
16
(P) Ground CAN-L
Input/Output ——
17
(R) Ground Battery power supply Input
AlwaysBattery voltage
18
(B) Ground Ground
—Always 0 V
19 — Motor —— —
20 — Motor —— —
Revision: May 2010
2011 Versa

STEERING WHEEL TURNING FORCE IS HEAVY OR LIGHTSTC-27
< SYMPTOM DIAGNOSIS > [EPS]
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STEERING WHEEL TURNING FO RCE IS HEAVY OR LIGHT
DescriptionINFOID:0000000005931263
Steering wheel turning force is heavy or light.
Diagnosis ProcedureINFOID:0000000005931264
1.CHECK THE ILLUMINATION OF THE EPS WARNING LAMP
Check that the EPS warning lamp turns ON when igni tion switch turns ON. Then, EPS warning lamp turns
OFF after the engine is started.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 2.
2.PERFORM SELF-DIAGNOSIS
With CONSULT-III
1. Turn the ignition switch OFF to ON.
2. Perform EPS control unit self-diagnosis.
Is any DTC detected?
YES >> Check the DTC. Refer to STC-24, "DTC Index".
NO >> GO TO 3.
3.CHECK EPS CONTROL UNIT SIGNAL
With CONSULT-III
1. Start the engine. CAUTION:
Stop the vehicle.
2. Turn steering wheel from full left stop to full right stop.
3. Select “TORQUE SENSOR” of “DATA MONITOR” for EPS control unit.
Is the inspection result normal?
YES >> GO TO 5.
NO >> GO TO 4.
4.CHECK EPS MOTOR
Perform the trouble diagnosis of EPS motor. Refer to STC-13, "
Diagnosis Procedure".
Is the inspection result normal?
YES >> GO TO 5.
NO >> Repair or replace the specific malfunctioning part.
5.CHECK STEERING WH EEL TURNING FORCE
Check the steering wheel turning force. Refer to PS-6, "
On-Vehicle Inspection and Service".
Is the inspection result normal?
YES >> Inspection End
NO >> Check the steering wheel turning force for mechanical malfunction. Refer to PS-6, "
On-Vehicle
Inspection and Service".
Monitor item ConditionDisplay value
TORQUE SENSOR Steering wheel: Not steer-
ing (There is no steering
force)
Approx. 0 Nm
Steering wheel: Right turn Positive value (Nm)
Steering wheel: Left turn Negative value (Nm)
Revision: May 2010 2011 Versa

STC-28
< SYMPTOM DIAGNOSIS >[EPS]
UNBALANCE STEERING WHEEL TURNING FORCE AND RETURN BETWEEN
RIGHT AND LEFT
UNBALANCE STEERING WHEEL TU RNING FORCE AND RETURN BE-
TWEEN RIGHT AND LEFT
DescriptionINFOID:0000000005931265
Unbalance steering wheel turning force and return between right and left.
Diagnosis ProcedureINFOID:0000000005931266
1.CHECK THE ILLUMINATION OF THE EPS WARNING LAMP
Check that the EPS warning lamp turns ON when igni tion switch turns ON. Then, EPS warning lamp turns
OFF after the engine is started.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Refer to STC-26, "
Diagnosis Procedure".
2.CHECK WHEEL ALIGNMENT
1. Check the wheel alignment. Refer to FSU-7, "
On-Vehicle Inspection and Service".
2. Perform EPS control unit self-diagnosis.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Adjustment of wheel alignment.
3.CHECK EPS CONTROL UNIT SIGNAL
With CONSULT-III
1. Start the engine. CAUTION:
Stop the vehicle.
2. Turn steering wheel from full left stop to full right stop.
3. Select “TORQUE SENSOR” of “DATA MONITOR” for EPS control unit.
Is the inspection result normal?
YES >> GO TO 5.
NO >> GO TO 4.
4.CHECK EPS MOTOR
Perform the trouble diagnosis of EPS motor. Refer to STC-13, "
Diagnosis Procedure".
Is the inspection result normal?
YES >> GO TO 5.
NO >> Repair or replace the specific malfunctioning part.
5.CHECK STEERING WHEEL TURNING FORCE
Check the steering wheel turning force. Refer to PS-6, "
On-Vehicle Inspection and Service".
Is the inspection result normal?
YES >> Inspection End.
NO >> Check the steering wheel turning force for mechanical malfunction. Refer to PS-6, "
On-Vehicle
Inspection and Service".
Monitor item ConditionDisplay value
TORQUE SENSOR Steering wheel: Not steer-
ing (There is no steering
force)
Approx. 0 Nm
Steering wheel: Right turn Positive value (Nm)
Steering wheel: Left turn Negative value (Nm)
Revision: May 2010 2011 Versa

UNBALANCE STEERING WHEEL TURNING FORCE (TORQUE VARIATION)
STC-29
< SYMPTOM DIAGNOSIS > [EPS]
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UNBALANCE STEERING WHEEL TU RNING FORCE (TORQUE VARIA-
TION)
DescriptionINFOID:0000000005931267
Unbalance steering wheel turning force (torque variation).
Diagnosis ProcedureINFOID:0000000005931268
1.CHECK THE ILLUMINATION OF THE EPS WARNING LAMP
Check that the EPS warning lamp turns ON when igni tion switch turns ON. Then, EPS warning lamp turns
OFF after the engine is started.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Refer to STC-26, "
Diagnosis Procedure".
2.CHECK STEERING COLU MN AND STEERING GEAR
Check the steering column assembly and steering gear assembly.
• Steering column assembly. Refer to PS-10, "
Removal and Installation".
• Steering gear assembly. Refer to PS-15, "
Disassembly and Assembly".
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace the specific malfunctioning part.
3.CHECK EPS CONTROL UNIT SIGNAL
With CONSULT-III
1. Start the engine. CAUTION:
Stop the vehicle.
2. Turn steering wheel from full left stop to full right stop.
3. Select “TORQUE SENSOR” of “DATA MONITOR” for EPS control unit.
Is the inspection result normal?
YES >> GO TO 5.
NO >> GO TO 4.
4.CHECK EPS MOTOR
Perform the trouble diagnosis of EPS motor. Refer to STC-13, "
Diagnosis Procedure".
Is the inspection result normal?
YES >> GO TO 5.
NO >> Repair or replace the specific malfunctioning part.
5.CHECK STEERING WH EEL TURNING FORCE
Check the steering wheel turning force. Refer to PS-6, "
On-Vehicle Inspection and Service".
Is the inspection result normal?
YES >> Inspection End.
NO >> Check the steering wheel turning force for mechanical malfunction. Refer to PS-6, "
On-Vehicle
Inspection and Service".
Monitor item ConditionDisplay value
TORQUE SENSOR Steering wheel: Not steer-
ing (There is no steering
force)
Approx. 0 Nm
Steering wheel: Right turn Positive value (Nm)
Steering wheel: Left turn Negative value (Nm)
Revision: May 2010 2011 Versa