2008 NISSAN LATIO torque

STC-1
STEERING
C
D
E
F
H
I
J
K
L
M
SECTION STC
A
B
STC
N
O
P
CONTENTS
STEERING CONTROL SYSTEM
EPS
SERVICE INFORMATION ............................
2
PRECAUTIONS ...................................................2
Precaution for Supplemental Restraint System
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" ...................................................................
2
Precaution Necessary for Steering Wheel Rota-
tion After Battery Disconnect .....................................
2
Service Notice or Precaution for EPS System ..........2
EPS SYSTEM ......................................................4
System Description ...................................................4
Schematic .................................................................5
CAN Communication .................................................5
TROUBLE DIAGNOSIS ......................................6
Fail-Safe Function .....................................................6
How to Perform Trouble Diagnosis ...........................6
Component Parts Location ........................................7
Wiring Diagram - EPS - .............................................8
EPS Control Unit Input/Output Signal Reference
Value .........................................................................
9
EPS Terminal and Reference Value ........................10
CONSULT-III Function (EPS) ..................................11
Symptom Chart ........................................................13
TROUBLE DIAGNOSIS FOR SYSTEM ............14
DTC C1601 BATTERY VOLT ..................................14
DTC C1604 TORQUE SENSOR .............................15
DTC C1606 EPS MOTOR .......................................16
DTC C1607 EEPROM .............................................17
DTC C1608 CONTROL UNIT ..................................17
DTC C1609 CAN VHCL SPEED .............................18
DTC C1610 CAN ENG RPM ...................................19
DTC U1000 CAN COMM CIRCUIT .........................19
Component Inspection .............................................19
TROUBLE DIAGNOSIS FOR SYMPTOMS ......21
EPS Warning Lamp Does Not Turn ON ..................21
EPS Warning Lamp Does Not Turn OFF ................21
Steering Wheel Turning Force Is Heavy or Light .....22
Unbalance Steering Wheel Turning Force and Re-
turn Between Right and Left ....................................
23
Unbalance Steering Wheel Turning Force (Torque
Variation) .................................................................
24

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]
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
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-10
< SERVICE INFORMATION >[EPS]
TROUBLE DIAGNOSIS
*1 : In the front of the value, “L” is displayed at steering left and “R” is displayed at steering right.
*2 : Almost in accordance with the value of “MOTOR SIG”. It is not a malfunction though these values are not accorded when steering
quickly.
*3 : It is not a malfunction, though it might not be corresponding just after ignition switch is turned ON.
*4 : It turns to OFF after waiting for a short period of time.
EPS Terminal and Reference ValueINFOID:0000000001703880
EPS HARNESS CONNECTOR TERMINAL LAYOUT
TERMINALS AND REFERENCE VALUES FOR EPS CONTROL UNIT
Monitor item (Unit) Content Condition Display value
MOTOR VOL (V)Power supply voltage for
EPS control unitIgnition switch: ON Battery voltage
TORQUE SENSOR (Nm)Steering wheel turning
forceEngine runningSteering wheel: Not
steering (There is no
steering force) 0.00 Nm
Steering wheel: Steer-
ing0 – 8.19 Nm
*1 (The value
is changed according to
steering left or right)
MOTOR SIG (A)Command current to EPS
motorEngine runningSteering wheel: Not
steering (There is no
steering force)0.00 A
Steering wheel: Steer-
ing0 – 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: Steer-
ing0 – 65.00 A
*2 (The value
is changed according to
steering left or right)
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%)
*3
WARNING LAMP (ON/OFF)EPS warning lamp condi-
tionEPS warning lamp: ON ON
EPS warning lamp: OFF OFF
DERATING STAT (ON/OFF) Protect overload status Engine runningSteering wheel: Nor-
mal steeringOFF
Steering wheel: Steer-
ing over the stopON
*4
ENGINE STATUS (RUN/STOP) Engine statusEngine stopped
(Engine speed: Less than 400 rpm)STOP
Engine running
(Engine speed: 400 rpm or more)RUN
SGIA1624E

TROUBLE DIAGNOSIS
STC-11
< SERVICE INFORMATION >[EPS]
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
Data are reference values and are measured between each terminal and ground.
CAUTION:
When using a circuit tester to measure voltage for inspection, be sure not to extend forcibly any connector terminals.
CONSULT-III Function (EPS)INFOID:0000000001703881
FUNCTION
CONSULT-III can display each diagnostic item using the diagnostic test modes shown following.
SELF-DIAG RESULTS MODE
Display Item List
Te r m i n a lWire
colorItem Condition Data (Approx.)
4 V Torque sensor sub Engine runningSteering wheel: Not steering
(There in no steering force)2.5 V
Steering wheel: Steering1.7 V – 3.3 V
(The value is changed accord-
ing to steering left or right)
5 BR Torque sensor power supplyIgnition switch: ON 8 V
Ignition switch: OFF 0 V
6 G Torque sensor main Engine runningSteering wheel: Not steering
(There is no steering force)2.5 V
Steering wheel: Steering1.7 V – 3.3 V
(The value is changed accord-
ing to steering left or right)
7 R Torque sensor ground Always 0 V
9 L CAN-H — —
10 O Power supplyIgnition switch: ON Battery voltage
Ignition switch: OFF 0 V
16 P CAN-L — —
17 R Power supply (Memory back-up)Ignition switch: ON Battery voltage
Ignition switch: OFF Battery voltage
18 B Ground Always 0 V
19 — Motor (+) — —
20 — Motor (–) — —
Diagnostic test mode Function Reference page
Self-diagnostic results • Self-diagnostic results can be read and erased quickly."SELF-DIAG
RESULTS
MODE"
Data monitor • Input/Output data in the EPS control unit can be read."DATA MONI-
TOR"
CAN diagnostic support monitor • The results of transmit/receive diagnosis of CAN communication can be read.LAN-6
ECU part number • EPS control unit part number can be read."EPS CON-
TROL UNIT
PART NUM-
BER"

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

TROUBLE DIAGNOSIS
STC-13
< SERVICE INFORMATION >[EPS]
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
Symptom ChartINFOID:0000000001703882
If EPS warning lamp turns ON, perform self-diagnosis. Refer to STC-11, "CONSULT-III Function (EPS)" .
Symptom Condition Check item Reference page
EPS warning lamp does not turn ON when ig-
nition switch to “ON”.
(EPS warning lamp check)Ignition switch: ONCAN communication line
STC-21
Combination meter
EPS warning lamp does not turn OFF for sev-
eral seconds after starting the engineEngine runningCAN communication line
STC-21
Power supply and ground for
EPS control unit
Torque sensor
EPS motor
Vehicle speed signal
Engine status signal
Combination meter
Steering wheel turning force is heavy or light,
while driving• While driving
• Steering wheel turningCAN communication line
STC-22
Vehicle speed signal
Engine status signal
EPS motor
Steering wheel turning force
(Mechanical malfunction)
Unbalance steering wheel turning force and
return between right and left, while driving• While driving
• Steering wheel turningWheel alignment
STC-23
Steering wheel turning force
(Mechanical malfunction)
Unbalance steering wheel turning force,
while driving (Torque variation)• While driving
• Steering wheel turningSteering column intermediate
shaft installation condition
STC-24
Steering wheel turning force
(Mechanical malfunction)

TROUBLE DIAGNOSIS FOR SYSTEM
STC-15
< SERVICE INFORMATION >[EPS]
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
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)