Infiniti Q45. Manual

ELECTRICALLY CONTROLLED POWER STEERING SYSTEM

STC-7

[WITHOUT REAR ACTIVE STEER]

STC

System Diagram

NGS0005W

COMPONENTS FUNCTION DESCRIPTION

SGIA1395E

Component parts

Function

Active damper suspension control unit

Controls power steering solenoid valve (with fail-safe function).

Power steering solenoid valve

Controls oil pressure in gear housing assembly.

Combination meter

Combination meter sends vehicle speed signal to active damper suspension control unit.

ECM

ECM sends engine speed signal to active damper suspension control unit. (For fail-safe
conditions)

STC-8

[WITHOUT REAR ACTIVE STEER]

TROUBLE DIAGNOSIS

PFP:00004

Fail-Safe Function

NGS00061

Fail-safe function starts under the vehicle conditions listed below.

FAIL-SAFE INPUT CONDITIONS

NOTE:
When the engine is revved up to 1,500 rpm or more for at least 10 seconds with vehicle at standstill, the fail-
safe function operates; however, this is not a matter of concern. The fail-safe function can be released by driv-
ing vehicle of a speed of greater than 1.4 km/h (0.9 MPH) or by turning ignition switch from “OFF” to “ON”.

●

The fail-safe function operates to regulate power steering sole-
noid valve operation in response to engine speed, thereby main-
taining the required power steering force.

How to Perform Trouble Diagnosis

NGS00062

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-15, "ERASE SELF-DIAGNOSIS"

●

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

Fail-safe input conditions

Release conditions

No vehicle speed signal entered for at least 10 seconds while driving
at an engine speed of greater than 1,500 rpm.

●

A vehicle speed signal of greater than 1.4 km/h (0.9 MPH)
is entered.

●

Ignition switch is turned from “OFF” to “ON”.

A vehicle speed signal of greater than 30 km/h (19 MPH) or abruptly
drops below 2 km/h (1 MPH).

SST697CB

SEF233G

SEF234G

TROUBLE DIAGNOSIS

STC-9

[WITHOUT REAR ACTIVE STEER]

STC

Component Parts Location

NGS0005Y

SGIA1398E

Infiniti Q45. Manual - part 876