NISSAN LATIO 2007 Service Repair Manual

EPS SYSTEM
STC-5
[EPS]
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Revision: June 20062007 Versa
EPS SYSTEMPFP:28500
System DescriptionUGS000A5
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
status). 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
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-II.
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

STC-6
[EPS]
EPS SYSTEM
Revision: June 20062007 Versa
System DiagramUGS000A6
COMPONENTS FUNCTION DESCRIPTION
CAN CommunicationUGS000A7
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-47, "
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
using 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

TROUBLE DIAGNOSIS
STC-7
[EPS]
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Revision: June 20062007 Versa
TROUBLE DIAGNOSISPFP:00004
Fail-Safe FunctionUGS0008G

If any malfunction occurs in the system, and control unit detects the malfunction, EPS warning lamp on
combination meter turns ON to indicate system malfunction.

When EPS warning lamp is ON, enters a manual steering state. (Control turning force steering wheel
becomes heavy.)
How to Perform Trouble DiagnosisUGS00090
BASIC CONCEPT

To perform trouble diagnosis, it is the must to have understanding about vehicle systems (control and
mechanism) thoroughly.

It is also important to clarify customer complaints before starting
the inspection.
First of all, reproduce the symptoms, and understand them fully.
Ask customer about his/her complaints carefully. In some cases,
it will be necessary to check symptoms by driving vehicle with
customer.
CAUTION:
Customers are not professionals. It is dangerous to make
an easy guess like “maybe the customer means that...” or
“maybe the customer mentions this symptom”.

It is essential to check symptoms right from the beginning in
order to repair malfunctions completely.
For intermittent malfunctions, reproduce symptoms based on
interview with customer and past examples. Do not perform
inspection on ad hoc basis. Most intermittent malfunctions are
caused by poor contacts. In this case, it will be effective to shake
suspected harness or connector by hand. When repairing with-
out any symptom diagnosis, you cannot judge if malfunctions
has actually been eliminated.
PRECAUTIONS FOR TROUBLE DIAGNOSIS

Be sure to check the procedures of the trouble diagnosis in advance. Refer to STC-7, "How to Perform
Trouble Diagnosis" .

Always erase memory after completing trouble diagnosis. Refer to STC-13, "How to Erase Self-Diagnostic
Results" .

Checking continuity and voltage between units, be sure to check connector terminals for disconnection,
looseness, bend, or collapse. Repair or replace applicable part if any non-standard condition is detected.

Be careful not to forcibly extend any connector terminal if a circuit tester is used for the check.

Always confirm the general precautions. Refer to GI-4, "General Precautions" .
INTERVIEW

Complaints vary depending on the person. It is important to clar-
ify the customer's actual remarks.

Ask the customer about what symptoms occur under what con-
ditions. Use the information to reproduce the symptom of con-
firm by vehicle.
SEF 2 33 G
SEF 2 34 G
SEF 9 07 L

STC-8
[EPS]
TROUBLE DIAGNOSIS
Revision: June 20062007 Versa
Component Parts LocationUGS0007U
SGIA1623E

TROUBLE DIAGNOSIS
STC-9
[EPS]
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Revision: June 20062007 Versa
Wiring Diagram — EPS —UGS0007W
BGWA0001E

STC-10
[EPS]
TROUBLE DIAGNOSIS
Revision: June 20062007 Versa
BGWA0002E

TROUBLE DIAGNOSIS
STC-11
[EPS]
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Revision: June 20062007 Versa
EPS Control Unit Input/Output Signal Reference ValuesUGS0007X
SPECIFICATIONS WITH CONSULT-II
CAUTION:
The output signal indicates the EPS control unit calculation date. The normal values will be displayed
even in the event that the output circuit (harness) is open.
*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.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

STC-12
[EPS]
TROUBLE DIAGNOSIS
Revision: June 20062007 Versa
SPECIFICATIONS BETWEEN EPS CONTROL UNIT TERMINALS
EPS Control Unit Terminal Connector Layout
Data are reference value and are measured.
CAUTION:
When using a circuit tester to measure voltage for inspection, be sure not to extend forcibly any connector terminals.
SGIA1624E
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 (–) — —

TROUBLE DIAGNOSIS
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Revision: June 20062007 Versa
CONSULT-II Function (EPS)UGS0007Y
FUNCTION
CONSULT-II can display each diagnostic item using the diagnostic test modes shown following.
CONSULT-II SETTING PROCEDURE
Refer to GI-38, "CONSULT-II Start Procedure" .
SELF-DIAG RESULTS MODE
Operation Procedure
1. Perform “CONSULT-II Start Procedure”. Refer to GI-38, "CONSULT-II Start Procedure" .
2. With engine at idle, touch “SELF-DIAG RESULTS”. Display
shows malfunction experienced since the last erasing operation.
NOTE:

When malfunction occurred at the same time, it is dis-
played to a 3 system at the maximum.

The details for “TIME” are as follow:
–“0”: Error currently detected with EPS control unit.
–Except for “0”: Error detected in the past and memorized
with EPS control unit.
Detects frequency of driving after DTC occurs (frequency
of turning ignition switch “ON”).
Display Item List
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.
Diagnostic test mode Function Reference page
Self-diagnostic results

Self-diagnostic results can be read and erased quickly.STC-13
Data monitor
Input/Output data in the EPS control unit can be read.STC-14
CAN diagnostic support monitor
The results of transmit/receive diagnosis of CAN communication can be read.LAN-44
ECU part number
EPS control unit part number can be read.STC-14
SGIA1531E
Item
(CONSULT-II 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-16, "
DTC C1601
BATTERY VOLT"
TORQUE SENSOR
[C1604]When the torque sensor malfunction assembled in steering column
assembly is detected. STC-19, "DTC C1604
TORQUE SENSOR"
EPS MOTOR
[C1606]When the motor driver malfunction of EPS control unit or EPS motor
malfunction is detected.STC-21, "DTC C1606
EPS MOTOR"
EEPROM
[C1607]When the memory (EEPROM) system malfunction is detected in
EPS control unit.STC-22, "DTC C1607
EEPROM"
CONTROL UNIT
[C1608]When the internal malfunction is detected in EPS control unit.STC-22, "DTC C1608
CONTROL UNIT"
CAN VHCL SPEED
[C1609]When the malfunction is detected in vehicle speed signal received
with CAN communication.STC-23, "DTC C1609
CAN VHCL SPEED"
CAN ENG RPM
[C1610]When the malfunction is detected in engine status signal received
with CAN communication.STC-24, "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-24, "DTC U1000
CAN COMM CIRCUIT"
NO DTC IS DETECTED.
FURTHER TESTING MAY BE
REQUIRED.No NG item has been detected. —

STC-14
[EPS]
TROUBLE DIAGNOSIS
Revision: June 20062007 Versa
2. Turn ignition switch “OFF” to erase memory.
3. Turn ignition switch “ON” and select “SELF-DIAG RESULTS” mode with CONSULT-II.
4. Touch “ERASE” on CONSULT-II screen to erase DTC memory.
CAUTION:
If memory cannot be erased, perform diagnosis.
DATA MONITOR
Operation Procedure
1. Perform “CONSULT-II Start Procedure”. Refer to GI-38, "CONSULT-II Start Procedure" .
2. Touch “DATA MONITOR”.
3. Select from “SELECT MONITOR ITEM”, screen of data monitor mode is displayed.
NOTE:
When malfunction is detected, CONSULT-II performs REAL-TIME DIAGNOSIS. Also, any malfunc-
tion detected while in this mode will be displayed at real time.
Display Item List
EPS CONTROL UNIT PART NUMBER
Display a part number of EPS control unit carried by a vehicle.
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
SGIA1532E