Nissan Sentra. Manual — part 825

COMPONENT PARTS

STC-7

< SYSTEM DESCRIPTION >

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

EPS motor provides the assist torque by the control signal from EPS control unit.

TORQUE SENSOR

Torque sensor detects the steering torque, and transmits 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.

STC-8

< SYSTEM DESCRIPTION >

SYSTEM

SYSTEM

EPS SYSTEM
EPS SYSTEM : System Description

INFOID:0000000009757424

SYSTEM DIAGRAM

DESCRIPTION

• 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 con-

dition.

• In case of a malfunction in the electrical system, the fail-safe func-

tion stops output signals to the EPS motor. Refer to

STC-9, "EPS

SYSTEM : Fail-Safe"

.

• 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). Refer to

STC-13, "Protection Func-

tion"

.

• Extensive steering at low speed will cause the EPS control unit

and EPS motor to heat up, once temperature reaches critical point

EPS control unit will reduce current to reduce heat up. System will

recover as temperature lowers (reduced or no assistance).

EPS WARNING LAMP INDICATION

• Turn ON when there is a malfunction in EPS system. If 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.

CAUTION:

JSGIA1097GB

JSGIA0832GB

Condition

EPS warning lamp

Ignition switch ON. (Lamp check)

ON

Engine running.

OFF

EPS system malfunction [Other diagnostic item]

ON

SYSTEM

STC-9

< SYSTEM DESCRIPTION >

C

D

E

F

H

I

J

K

L

M

A

B

STC

N

O

P

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

EPS SYSTEM : Fail-Safe

INFOID:0000000009757425

• 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:0000000009757426

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.

WARNING/INDICATOR/CHIME LIST
WARNING/INDICATOR/CHIME LIST : Warning Lamp/Indicator Lamp

INFOID:0000000009757427

Name

Design

Layout/Function

EPS warning lamp

For layout, refer to

STC-9, "WARNING/INDICATOR/CHIME LIST : Warning Lamp/Indicator

Lamp"

.

For function, refer to

STC-9, "WARNING/INDICATOR/CHIME LIST : Warning Lamp/Indicator

Lamp"

.

STC-10

< SYSTEM DESCRIPTION >

DIAGNOSIS SYSTEM (EPS CONTROL UNIT)

DIAGNOSIS SYSTEM (EPS CONTROL UNIT)

CONSULT Function

INFOID:0000000009757428

FUNCTION

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

*: The following diagnosis information is cleared by erasing.

• DTC

• Freeze frame data (FFD)

ECU IDENTIFICATION

Displays the part number stored in the control unit.

SELF-DIAG RESULTS MODE

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 MODE

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

to this vehicle, refer to CONSULT display items.

Diagnostic test 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 ignition 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 ignition 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.

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) or (°F)

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.

*2

VEHICLE SPEED (km/h) or (MPH)

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

*3

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.