Infiniti M45 (Y34). Manual - part 795

ELECTRICALLY CONTROLLED POWER STEERING SYSTEM

STC-5

[EPS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

TGWA0009E

STC-6

[EPS]

ELECTRICALLY CONTROLLED POWER STEERING SYSTEM

Control Unit Input/Output Signal Standard

AGS0003I

The standard values (voltage), measured with an analog tester in contact with control unit terminal, are shown
below:

Measuring 

terminal

Measuring point

Standard value

+

–

1

Ground

Ignition switch ON or 
START

Ignition switch ON

Battery voltage (approx. 12V)

2

Ground

—

0V

3

Vehicle speed signal

When the speed is very low, the 
voltage fluctuates between 
approximately 0V and approxi-
mately 5V or higher.

When vehicle speed is approx. 40 km/h (25 MPH)

5

Engine revolution signal

Engine is running

●

Warm-up condition

●

Engine idle speed

Engine is running

●

Warm-up condition

●

Engine speed is 2,000 rpm

7

Solenoid valve

Engine is running

Normal

0 km/h ((0 MPH) : Approx. 4.4 - 6.6V
100 km/h (62 MPH): Approx. 2.4 - 3.6V

When the fail-safe function is activated:

0 - 1,500 rpm : Approx. 4.4 - 6.6V
1,500 - 3,000 rpm : Approx. 3.5V
3,000 rpm or more : Approx. 2.1V

ELF1080D

PBIA3654J

PBIA3655J

ELECTRICALLY CONTROLLED POWER STEERING SYSTEM

STC-7

[EPS]

C

D

E

F

H

I

J

K

L

M

A

B

STC

Trouble Diagnosis

AGS0003H

PRECAUTIONS FOR DIAGNOSIS

Intermittent incidents may be caused by malfunctioning harness, harness connector or terminal. Move har-
nesses, harness connectors or terminals by hand to make sure that there is no contact malfunction.
If a circuit tester for measuring voltage is used for check, be careful not to forcibly spread any connector termi-
nals.

INSPECTION BEFORE TROUBLE DIAGNOSIS

●

Check power steering fluid level and check for any leak. Refer to 

PS-6, "POWER STEERING FLUID"

 .

DIAGNOSIS PROCEDURE
Symptom:

●

Heavy steering operation during stationary turns

●

Light steering operation during high-speed driving

Inspection procedure

1. 

CHECK POWER STEERING CONTROL UNIT POWER CIRCUIT

1.

Disconnect power steering control unit harness connector.

2.

Check voltage between power steering control unit harness con-
nector M108 terminal 1 (GY) and ground.

OK or NG

OK

>> GO TO 2.

NG

>> Check the following.

●

10A fuse [No.7, located in fuse block (J/B) No.1]

●

Harness for open or short between power steering
control unit and fuse.

●

If there is any non-standard condition, repair or
replace it.

2. 

CHECK POWER STEERING CONTROL UNIT GROUND CIRCUIT

Check continuity between power steering control unit harness con-
nector M108 terminal 2 (B) and ground.

OK or NG

OK

>> GO TO 3.

NG

>> Repair or replace power steering control unit ground

harness.

: Battery voltage should exist.

SGIA0328E

 2 (B) - Ground

: Continuity should exist.

SGIA0329E

STC-8

[EPS]

ELECTRICALLY CONTROLLED POWER STEERING SYSTEM

3. 

CHECK SOLENOID VALVE SIGNAL 1 

1.

Connect power steering control unit harness connector.

2.

Start engine and gradually increase the vehicle speed from 0 to
100 km/h (0 to 62 MPH).

3.

Check voltage between power steering control unit harness con-
nector M108 terminal 7 (LG) and ground.

OK or NG

OK

>> GO TO 4.

NG

>> GO TO 9.

4. 

CHECK SOLENOID VALVE SIGNAL 2 

1.

When engine is running at idle, change the engine speed to
approximately 1,600 rpm and then to approximately 3,000 rpm.

2.

Check voltage between power steering control unit harness con-
nector M108 terminal 7 (LG) and ground.

OK or NG

OK

>> GO TO 5.

NG

>> GO TO 10.

5. 

CHECK SOLENOID VALVE 

●

Disconnect power steering control unit and solenoid valve con-
nectors.

●

Check continuity between power steering control unit harness
connector M108 terminal 7 (LG) and solenoid valve harness
connector F3 terminal 1 (LG).

OK or NG

OK

>> GO TO 6.

NG

>> Check harness for open or short between power steer-

ing control unit and solenoid valve.

6. 

CHECK SOLENOID VALVE HARNESS

●

Check continuity between solenoid valve harness connector F3
terminal 2 (B) and ground.

OK or NG

OK

>> GO TO 7.

NG

>> Repair or replace solenoid valve ground harness.

: Make sure that voltage changes from approxi-
mately 5.5V to approximately 2.5V.

SGIA0330E

: Make that voltage changes from approximately 
5.5V to approximately 2.1V in steps.

SGIA0331E

7 (LG) – 1 (LG)

: Continuity should exist.

SGIA0332E

 2 (B) – Ground

: Continuity should exist.

SGIA0333E