Nissan March K13. Manual - part 633

SYSTEM

STC-7

< SYSTEM DESCRIPTION >

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SYSTEM

EPS SYSTEM

EPS SYSTEM : System Description

INFOID:0000000005912711

• 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.

• 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.

SYSTEM DIAGRAM

INPUT/OUTPUT SIGNAL

Communicates the signal from each control unit via CAN communication. 

*1

: With ABS models 

JPGIB0005GB

Control unit

Signal status

ECM

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

ABS actuator and electric unit (con-

trol unit)

*1

Transmits mainly the following signals to EPS control unit via CAN communication. 

• Vehicle speed signal

*1

Combination meter

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

EPS warning lamp signal is received from the EPS control unit via CAN communication. 

STC-8

< SYSTEM DESCRIPTION >

SYSTEM

EPS WARNING LAMP INDICATION

CAUTION:

EPS warning lamp also turns ON due to data reception error, CAN communication error etc.

EPS SYSTEM : Fail-Safe

INFOID:0000000005912779

• If any malfunction occurs in the system, and control unit detects the malfunction, EPS warning lamp on com-

bination meter turns ON to indicate system malfunction.

• When EPS warning lamp is ON, enters into a manual steering state. (Control turning force steering wheel

becomes heavy.)

EPS SYSTEM : Protection Function

INFOID:0000000006021884

EPS control unit decreases the output signal to EPS motor while extremely using the power steering function
(e.g., full steering) consecutively for protecting 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.

Condition

EPS warning lamp

Ignition switch ON. (Lamp check)

ON

Engine running.

OFF

EPS system malfunction [Other diagnostic item]

ON

DIAGNOSIS SYSTEM (EPS CONTROL UNIT)

STC-9

< SYSTEM DESCRIPTION >

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DIAGNOSIS SYSTEM (EPS CONTROL UNIT)

CONSULT-III Function

INFOID:0000000005912713

FUNCTION

CONSULT-III can display each diagnostic item using 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-12, "DTC Index"

.

DATA MONITOR MODE

Display Item List

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

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)

Displays the current commanded value to EPS motor.

ASSIST TORQUE (Nm)

Displays assist torque being output by the electric power steering.

C/U TEMP (

°

C)

Displays the temperature of the EPS control unit.

ASSIST LEVEL (%)

Normally displays 100%. In case of an excessive stationary steering, the assist 
curvature gradually falls. However, it return to 100% when left standing.

VEHICLE SPEED (km/h) or (MPH)

Vehicle 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.

STC-10

< ECU DIAGNOSIS INFORMATION >

EPS CONTROL UNIT

ECU DIAGNOSIS INFORMATION

EPS CONTROL UNIT

Reference Value

INFOID:0000000005912714

VALUES ON THE DIAGNOSIS TOOL

CAUTION:

The output signal indicates the EPS control unit calculation data. The 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 steering
quickly.

*2: A fixed value is indicated regardless of steering turning.

*3: Normally displays 100%. In case of an excessive stationary steering, the assist curvature gradually falls. However, it returns to 100%
when left standing.

*4: It is not a malfunction, though it might not be corresponding just after ignition switch in turned ON.

Monitor item 

Display content

Data monitor

Condition

Display value

BATTERY VOLT

Power supply voltage for 
EPS control unit

Ignition switch: ON

Battery voltage

TORQUE SENSOR

Steering wheel turning 
force

Engine running

Steering 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 running

Steering 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 running

Steering 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)

ASSIST TORQUE

Displays assist torque 
being output by the EPS.

Engine running

Approx. 0 Nm

*2

C/U TEMP

Displays temperature of 
the EPS control unit.

Ignition switch ON or engine running

Displays temperature of in-
side of EPS control unit (

°

C)

ASSIST LEVEL

Assist available level

Engine running

100 % 

*3

VEHICLE SPEED

Vehicle speed

Vehicle stopped

0 km/h (0 mph)

While driving

Approximately equal to the 
indication on speedometer

(inside of 

±

10%)

*4

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