Nissan Leaf. Manual - part 1141

SYSTEM

STC-9

< SYSTEM DESCRIPTION >

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CAUTION:

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

EPS SYSTEM : Fail-Safe

INFOID:0000000010119184

• 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, the system enters into a manual steering state. (Control turning force steer-

ing wheel becomes heavy.)

• Under abnormal vehicle speed signal conditions, vehicle speed is judged as constant.

EPS SYSTEM : Protection Function

INFOID:0000000010119185

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 is recovered if the steering wheel is not turned for a

while.

When vehicle is READY state

OFF

EPS system malfunction [Other diagnostic item]

ON

Condition

EPS warning lamp

STC-10

< SYSTEM DESCRIPTION >

DIAGNOSIS SYSTEM (EPS CONTROL UNIT)

DIAGNOSIS SYSTEM (EPS CONTROL UNIT)

CONSULT Function

INFOID:0000000010119186

APPLICATION ITEMS

CONSULT can display each diagnostic item using the diagnostic test modes shown following.

*: The following diagnosis information is erased by erasing.

• DTC

• Freeze frame data (FFD)

ECU IDENTIFICATION

Displays the part number stored in the control unit.

SELF-DIAGNOSTIC RESULT

Refer to 

STC-14, "DTC Index"

.

When “CRNT” is displayed on self-diagnosis result.

• The system is presently malfunctioning.

When “PAST” is displayed on self-diagnosis result.

• System malfunction in the past is detected, but the system is presently normal.

FREEZE FRAME DATA (FFD)

The following vehicle status is recorded when DTC is detected and is displayed on CONSULT.

DATA MONITOR

Diagnostic mode

Function

ECU identification

The part number stored in the control unit can be read.

Self diagnostic result

Self-diagnostic results and freeze frame data can be read and erased quickly.

*

Data monitor

Input/Output data in the EPS control unit can be read.

Item name

Display item

IGN COUNTER
(0 – 39)

The number of times that power switch is turned ON after the DTC is detected is displayed.
• When “0” is displayed: It indicates that the system is presently malfunctioning.
• When except “0” is displayed: It indicates that system malfunction in the past is detected, but the system is pres-

ently normal.
NOTE:
Each time when power switch is turned OFF to ON, numerical number increases in 1

→2→3...38→39.

When the operation number of times exceeds 39, the number do not increase and “39” is displayed until self-
diagnosis is erased.

Monitor item (Unit)

Remarks

BATTERY VOLT (V)

Displays the power supply voltage for EPS control unit.

STEERING ASSIST REQUEST (On/Off)

Condition of steering assist request is displayed from power steering start acti-
vation signal via CAN communication.

TORQUE SENSOR (Nm)

Displays steering wheel turning force detected by torque sensor.

MOTOR CURRENT (A)

Displays the current value consumed by EPS motor.

*1

MOTOR SIG (A)

Displays the current commanded value to EPS motor.

ASSIST TORQUE (Nm)

Displays assist torque of EPS motor being output by the electric power steering.

C/U TEMP [

°C (°F)]

Displays the temperature of inside of the EPS control unit.

ASSIST LEVEL (%)

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

*2

VEHICLE SPEED [km/h (MPH)]

Vehicle speed is displayed from vehicle speed signal via CAN communication.

*3

WARNING LAMP (On/Off)

EPS warning lamp control status is displayed.

DIAGNOSIS SYSTEM (EPS CONTROL UNIT)

STC-11

< SYSTEM DESCRIPTION >

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*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: Normally displays 100%. In case of an excessive stationary steering, the assist curvature gradually falls.

However, it returns to 100% when left standing.

*3: It is not a malfunction, though it might not be corresponding just after power switch is turned ON.

STC-12

< ECU DIAGNOSIS INFORMATION >

EPS CONTROL UNIT

ECU DIAGNOSIS INFORMATION

EPS CONTROL UNIT

Reference Value

INFOID:0000000010503214

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.

NOTE:

The following table includes information (items) inapplicable to this vehicle. For information (items) applicable

to this vehicle, refer to CONSULT display items.

*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: Normally displays 100%. In case of an excessive stationary steering, the assist curvature gradually falls.

However, it returns to 100% when left standing.

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

Monitor item 

Data monitor

Condition

Display value

BATTERY VOLT

Ignition switch: ON

Battery voltage

TORQUE SENSOR

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

Engine running

Steering wheel: Not steering (There is 
no steering force)

Approx. 0 A

Steering wheel: Right or left turn

Displays consumption current of 
EPS motor (A)

*1

MOTOR SIG

Engine running

Steering wheel: Not steering (There is 
no steering force)

Approx. 0 A

Steering wheel: Right turn

Positive value (A)

Steering wheel: Left turn

Negative value (A)

ASSIST TORQUE

Engine running

Steering wheel: Not steering (There is 
no steering force)

Approx. 0 Nm

Steering wheel: Right or left turn

Displays assist torque of EPS motor 
(Nm)

C/U TEMP

Ignition switch ON or engine running

Displays temperature of inside of 
EPS control unit (

°C) or (°F)

ASSIST LEVEL

Engine running

100 % 

*2

VEHICLE SPEED

Vehicle stopped

0 km/h (0 mph)

While driving

Approximately equal to the indication 
on speedometer

*3

(inside of 

±10%)

WARNING LAMP

EPS warning lamp: ON

On

EPS warning lamp: OFF

Off

ENGINE STATUS

Engine not running

Stop

Engine running

Run