Nissan Tiida C11. Manual - part 1220

DIAGNOSIS AND REPAIR WORKFLOW

STC-3

< BASIC INSPECTION >

[EPS]

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BASIC INSPECTION

DIAGNOSIS AND REPAIR WORKFLOW

Work Flow

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DETAIED FLOW

1.

COLLECT THE INFORMATION FROM THE CUSTOMER

Get the detailed information from the customer about the symptom (the condition and the environment when
the incident/malfunction occurred) using the diagnosis worksheet.

>> GO TO 2.

2.

PERFORM THE SELF-DIAGNOSIS

Check the DTC display with the self-diagnosis function. Refer to 

STC-7, "CONSULT-III Function (EPS)"

.

Is there any DTC displayed?

YES

>> GO TO 3.

NO

>> GO TO 4.

3.

PERFORM THE SYSTEM DIAGNOSIS

Perform the diagnosis applicable to the displayed DTC. Refer to 

STC-28, "DTC Index"

.

>> GO TO 6.

4.

CHECK THE WARNING LAMP FOR ILLUMINATION

Check that the warning lamp illuminate.
Is ON/OFF timing normal?

YES

>> GO TO 5.

NO

>> GO TO 2.

5.

PERFORM THE DIAGNOSIS BY SYMPTOM

Perform the diagnosis applicable to the symptom. 

>> GO TO 6.

6.

REPAIR OR REPLACE THE MALFUNCTIONING PARTS

Repair or replace the specified malfunctioning parts.

>> GO TO 7.

7.

FINAL CHECK

Perform the self-diagnosis again, and check that the malfunction is repaired completely. After checking, erase
the self-diagnosis memory. Refer to 

STC-7, "CONSULT-III Function (EPS)"

.

Is no other DTC present and the repair completed?

YES

>> INSPECTION END

NO

>> GO TO 3.

STC-4

< FUNCTION DIAGNOSIS >

[EPS]

EPS SYSTEM

FUNCTION DIAGNOSIS

EPS SYSTEM

System Diagram

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System Description

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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 pro-
tect 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-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

SGIA1649E

Condition

EPS warning lamp

Lamp check

Turns ON when ignition switch is turned ON.

Turns OFF after engine start.

EPS SYSTEM

STC-5

< FUNCTION DIAGNOSIS >

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Component Parts Location

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EPS system malfunction

ON

Other than above (system normal)

OFF

Condition

EPS warning lamp

1.

EPS warning lamp

2.

EPS control unit

3.

EPS motor

4.

Torque sensor

5.

Reduction gear

AWGIA0027ZZ

STC-6

< FUNCTION DIAGNOSIS >

[EPS]

EPS SYSTEM

Component Description

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CAN Communication

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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-30, "CAN System Specification Chart"

.

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.

ECM

Transmits the following signals via CAN communication to EPS control unit.
• Engine status signal

ABS actuator and electric unit (con-
trol unit)

Transmits the following signals via CAN communication to EPS control unit.
• Vehicle speed signal

Combination meter

Transmits the following signals via CAN communication to EPS control unit.
• Vehicle speed signal