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Nissan Sentra B18 (2020-2025) Service Manual / Steering / Steering Control System :: System Description

Nissan Sentra B18 (2020-2025) Service Manual: Steering Control System :: System Description

Component Parts. Electronic Power Steering System. Electronic Power Steering System

Component Parts Location

Component Parts Location

Steering gear assembly

: Nissan Sentra Vehicle front

No.

Component

Function

1.

ABS (Ant-lock Braking System) actuator and electric unit (control unit)

Transmits mainly the following signal to EPS control unit via CAN communication:

  • Nissan Sentra Vehicle speed signal (ABS)

Refer to Component Parts Location for detailed component location.

2.

ECM

(Engine Control Module)

  • Transmits mainly the following signal to EPS control unit via CAN communication:

    • Engine status signal

  • Receives mainly the following signal from EPS control unit via CAN communication:

    • Battery supply current signal

Refer to Component Parts Location for detailed component location.

3.

Combination meter

[EPS (Electric Power Steering) warning lamp]

  • Transmits mainly the following signal to EPS control unit via CAN communication:

    • Nissan Sentra Vehicle speed signal (Meter)

  • Turns ON the EPS warning lamp according to the signal from the EPS control unit via CAN communication.

Refer to Component Parts Location (Type A) or Component Parts Location (Type B) for detailed component location.

4.

Chassis control module (with built in steering angle sensor)

Transmits mainly the following signal to EPS control unit via CAN communication:

  • Steering angle sensor signal

Refer to Component Parts Location for detailed component location.

5.

Steering gear assembly

Torque sensor

Refer to Steering Gear Assembly.

6.

EPS (Electric Power Steering) control unit

7.

EPS (Electric Power Steering) motor

Steering Gear Assembly

Steering Gear Assembly

The steering gear assembly is primarily composed of torque sensor (1), EPS control unit (2) and EPS motor (3).

EPS CONTROL UNIT

By receiving steering angle sensor signal ,Nissan Sentra vehicle speed signal and torque sensor signal, the EPS control unit calculates the current of motor drive according to the driving conditions. The EPS control unit controls the EPS motor.

TORQUE SENSOR

Torque sensor detects the steering torque, and transmit the signal to EPS control unit.

EPS MOTOR

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

System. Eps System

System Description

System Description

SYSTEM DIAGRAM

INPUT SIGNAL AND OUTPUT SIGNAL

Communicates the signal from each control unit via CAN communication:

Control unit

Signal status

ECM

Transmits the following signals to EPS control unit via CAN communication:

  • Engine status signal

  • EPS assist request signal

ABS actuator and electric unit (control unit)

Transmits the following signal to EPS control unit via CAN communication:

  • Nissan Sentra Vehicle speed signal (ABS)

Combination meter

Transmits the following signal to EPS control unit via CAN communication:

  • Nissan Sentra Vehicle speed signal (combination meter)

Receives the following signal from EPS control unit via CAN communication:

  • EPS warning lamp signal

Chassis control module (with built in steering angle sensor)

Transmits the following signal to EPS control unit via CAN communication:

  • Steering angle sensor signal

DESCRIPTION

  • EPS system consists mainly of EPS control unit, EPS motor, torque sensor and steering gear assembly.

  • EPS system calculates a control signal to transmit to the EPS motor based on information received from ECM, ABS actuator and electric unit (control unit), Chassis control module (with built in steering angle sensor) and combination meter via CAN communication.

  • EPS control unit performs an arithmetical operation on data, such as steering wheel turning force (sensor signal) from the torque sensor, Nissan Sentra vehicle speed signal, etc. Then it generates an optimum assist torque signal to the EPS motor according to the driving condition.

  • After engine start, the EPS system performs control.

  • When a malfunction occurs in the system, the fail-safe function stops the EPS system (manual steering state) or restricts its operation (Constant steering assist level state). Refer to 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 Protection Function.

EPS WARNING LAMP INDICATION

  • Turns ON when there is a malfunction in EPS system. If ON, fail-safe mode is engaged and the system enters a manual steering state (turning force at steering wheel becomes heavy).

  • Also turns ON when ignition switch is ON, for purpose of lamp check. Turns OFF after the engine starts, if system is normal.

Condition

EPS warning lamp

Ignition switch ON. (Lamp check)

ON

Engine running

OFF

EPS system malfunction [Other diagnostic item]

ON

CAUTION:

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

Warning/indicator/chime List

Warning Lamp/indicator Lamp

Warning Lamp/Indicator Lamp

Name

Design

Layout/Function

EPS warning lamp

For layout, refer to Design (Type A).

For layout, refer to Design (Type B).

For function, refer to System Description.

Diagnosis System (eps Control Unit). Consult Function. Consult Function

CONSULT Function

APPLICATION ITEMS

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

Diagnosis mode

CGW Status

Description

Restricted Mode

Diag Test Mode

Open Mode

Self Diagnostic Result

Display

Display

Display

Display non-network DTC which EPS control unit memorizes

CGW Information

Display

Display

Display

  • Display the current CGW mode

  • Enables CGW to switch mode

Data Monitor

Display

Display

Display

Displays EPS control unit input/output data in real time

ECU Identification

Display

Display

Display

Displays EPS control unit part number

Configuration

Display

Display

Display

  • The Nissan Sentra vehicle specification that is written in EPS control unit can be displayed or stored

  • The vehicle specification can be written when EPS control unit is replaced

Network-DTC

Display

Display

Display

Display network DTC which EPS control unit memorizes when performing "Diagnosis (All System)".

CAN Diag Support Monitor*

Display

Display

Display

 Note:

The mode is indicated, but not monitored

*: Displays when performing "Diagnosis (All System)".

CGW INFORMATION

Display the diagnosis mode which a user can perform in Diag Test mode/Open Mode by switching the CGW status from Restricted mode to Diag Test Mode/Open Mode.

For the method of switching CAN Gateway status, refer to CONSULT Function.

SELF DIAGNOSTIC RESULT

Refer to 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 Nissan Sentra vehicle status is recorded when DTC is detected and is displayed on CONSULT:

Freeze Frame Data Item

Unit

Description

Ignition switch counter

(0 – 255)

The number of times that ignition switch is 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 presently normal.

    Note:

    Each time when ignition switch is OFF to ON, numerical number increases in 1→2→3...38→255. When the operation number of times exceeds 255, the number do not increase and “255” is displayed until self-diagnosis is erased.

Mileage

km

-

DATA MONITOR

Note:

The following table includes information (items) inapplicable to this Nissan Sentra vehicle: For information (items) applicable to this vehicle, refer to CONSULT display items.

Monitor item

Unit

Remarks

Steering torque

Nm

Displays steering torque detected by torque sensor.

Assist level

%

Displays the current percentage of the allowable assist ratio EPS motor.

EPS warning

No error / Error1 / Error2 / not used

EPS warning status is displayed.

Demanded assistance torque

Nm

Displays the assist torque of EPS motor being output by the EPS control unit.

Measured motor current

A

Displays the current value consumed by EPS motor.

ECU temperature

°C

Displays the temperature of the EPS control unit.

Battery voltage

V

Displays the power supply voltage.

Nissan Sentra Vehicle speed

KPH

Display the Nissan Sentra vehicle speed from vehicle speed signal via CAN communication.

ENGINE STATUS

Status1 / Status2 / Status3

Displays the engine status based on the engine status.

ECU IDENTIFICATION

Displays the part number stored in the control unit.

CONFIGURATION

Programming includes the following functions:

Function

Description

Configuration

Before replacing ECU

  • Allows the reading of Nissan Sentra vehicle specification (parts number) written in EPS control unit to store the specification in CONSULT.

  • Allows the saving of Nissan Sentra vehicle specification (parts number) written in EPS control unit to store the specification in CONSULT.

After replacing ECU

Allows the writing of Nissan Sentra vehicle information (parts number) stored in CONSULT into the EPS control unit.
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