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Infiniti Q45. Manual - part 884

REAR ACTIVE STEER SYSTEM

STC-39

[WITH REAR ACTIVE STEER]

STC

COMPONENTS FUNCTION DESCRIPTION

CAN Communication

NGS00072

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-35, "CAN COMMUNICATION"

Component parts

Function

RAS control unit

Controls power steering solenoid valve and RAS actuator assembly (with fail-safe function).

Power steering solenoid valve

Controls oil pressure in gear housing assembly.

RAS actuator assembly

Moves the rear wheel angle.

Rear wheel steering angle sensor

Transmits RAS actuator assembly condition to RAS control unit.

RAS motor

Operates RAS actuator assembly.

RAS warning lamp

Illuminates if malfunction is detected in electrical system of rear active steer system.

Stop lamp switch

Detects status of brake pedal depressed.

Steering angle sensor

Transmits steering angle sensor signal via CAN communication to RAS control unit.

ECM

Transmits engine speed signal via CAN communication to RAS control unit.

VDC/TCS/ABS control unit

Transmits the following signals via CAN communication to RAS control unit.

●

Vehicle speed signal

●

VDC malfunction signal

STC-40

[WITH REAR ACTIVE STEER]

TROUBLE DIAGNOSIS

PFP:00004

Fail-Safe Function

NGS0006L

●

If any malfunction occurs in rear active steer system, and control unit detects the malfunction, RAS warn-
ing lamp on combination meter turns ON to indicate system malfunction.

●

Stops the rear wheel control when the RAS warning lamp is turned ON.

●

The fail-safe function of vehicle speed signal operate to regulate
power steering solenoid valve operation in response to engine
speed, thereby maintaining the required power steering force.

How to Perform Trouble Diagnosis

NGS0006M

BASIC CONCEPT

●

To perform trouble diagnosis, it is the most important to have understanding about vehicle systems (con-
trol and mechanism) thoroughly.

●

It is also important to clarify customer complaints before inspec-
tion.
First of all, reproduce symptoms, and understand them fully.
Ask customer about his/her complaints carefully. In some cases,
it will be necessary to check symptoms by driving vehicle with
customer.

CAUTION:

Customers are not professional. It is dangerous to make an
easy guess like “maybe the customer means that...,” or
“maybe the customer mentions this symptom”.

●

It is essential to check symptoms right from the beginning in
order to repair malfunctions completely.
For intermittent malfunctions, reproduce symptoms based on
interview with customer and past examples. Do not perform
inspection on ad hoc basis. Most intermittent malfunctions are
caused by poor contacts. In this case, it will be effective to shake
suspected harness or connector by hand. When repairing with-
out any symptom diagnosis, you cannot judge if malfunctions
have actually been eliminated.

●

After completing diagnosis, always erase diagnostic memory.
Refer to

STC-54, "ERASE SELF-DIAGNOSIS"

●

For intermittent malfunctions, move harness or harness connec-
tor by hand. Then check for poor contact or reproduced open circuit.

SST697CB

SEF233G

SEF234G