Infiniti FX35 / FX45. Manual - part 413

DTC P0550 PSP SENSOR

EC-413

< SERVICE INFORMATION >

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DTC P0550 PSP SENSOR

Component Description

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Power steering pressure (PSP) sensor is installed to the power
steering high-pressure tube and detects a power steering load. This
sensor is a potentiometer which transforms the power steering load
into output voltage, and emits the voltage signal to the ECM. The
ECM controls the electric throttle control actuator and adjusts the
throttle valve opening angle to increase the engine speed and
adjusts the idle speed for the increased load.

CONSULT-III Reference Value in Data Monitor Mode

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Specification data are reference values.

On Board Diagnosis Logic

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The MIL will not light up for this self-diagnosis.
NOTE:
If DTC P0550 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643.
Refer to 

EC-424

.

DTC Confirmation Procedure

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NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.

1.

Start engine and let it idle for at least 5 seconds.

2.

Check 1st trip DTC.

3.

If 1st trip DTC is detected, go to 

EC-415, "Diagnosis Procedure"

.

PBIB1579E

MONITOR ITEM

CONDITION

SPECIFICATION

PW/ST SIGNAL

• Engine: After warming up, idle the 

engine

Steering wheel: Not being turned.

OFF

Steering wheel: Being turned.

ON

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0550
0550

Power steering pressure 
sensor circuit

An excessively low or high voltage from the 
sensor is sent to ECM.

• Harness or connectors

(Power steering pressure sensor circuit is 
open or shorted)

• Power steering pressure sensor

EC-414

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DTC P0550 PSP SENSOR

Wiring Diagram

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Specification data are reference values and are measured between each terminal and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

TBWM0302E

DTC P0550 PSP SENSOR

EC-415

< SERVICE INFORMATION >

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Diagnosis Procedure

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1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten ground screw on the body. Refer to 

EC-144, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK POWER STEERING PRESSURE (PSP) SENSOR POWER SUPPLY CIRCUIT

1.

Disconnect power steering pressure (PSP) sensor harness con-
nector.

2.

Turn ignition switch ON.

TER-

MI-

NAL 

NO.

WIRE 

COLOR

ITEM

CONDITION

DATA (DC Voltage)

12

R/G

Power steering pressure 
sensor

[Engine is running]
• Steering wheel: Being turned.

0.5 - 4.5V

[Engine is running]
• Steering wheel: Not being turned.

0.4 - 0.8V

67

B/W

Sensor ground

[Engine is running]
• Warm-up condition
• Idle speed

Approximately 0V

68

BR

Sensor power supply
(Power steering pressure 
sensor)

[Ignition switch: ON]

Approximately 5V

PBIB2625E

PBIB1579E

EC-416

< SERVICE INFORMATION >

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DTC P0550 PSP SENSOR

3.

Check voltage between PSP sensor terminal 1 and ground with
CONSULT-III or tester.

OK or NG

OK

>> GO TO 3.

NG

>> Repair open circuit or short to ground or short to power

in harness or connectors.

3.

CHECK POWER STEERING PRESSURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check harness continuity between PSP sensor terminal 3 and ECM terminal 67.
Refer to Wiring Diagram.

4.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 4.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

4.

CHECK POWER STEERING PRESSURE SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check harness continuity between ECM terminal 12 and PSP sensor terminal 2.
Refer to Wiring Diagram.

2.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 5.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

5.

CHECK POWER STEERING PRESSURE SENSOR

Refer to 

EC-416, "Component Inspection"

.

OK or NG

OK

>> GO TO 6.

NG

>> Replace power steering pressure sensor.

6.

CHECK INTERMITTENT INCIDENT

Refer to 

EC-139

.

>> INSPECTION END

Component Inspection

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POWER STEERING PRESSURE SENSOR

1.

Reconnect all harness connectors disconnected.

2.

Start engine and let it idle.

Voltage: Approximately 5V

PBIB0188E

Continuity should exist.

Continuity should exist.