Fuel System > Engine Control System > P0552 Power Steering Pressure Sensor/Switch Circuit Low input

Component Location

General Description

To reduce the required power to manipulate steering wheel, hydraulic pressure is used in power steering system. A load is sensed at steering oil pressure sensor then inputted to PCM as a wheel position signal. Controlling idle speed valve, PCM performs appropriate electric load correction With this signal.

DTC Description

Checking output signals from P/S PS(power steering pressure sensor) every 2.5 sec. under detecting condition, if an signal below 0.05V lasts for more than 1.25 sec., PCM sets P0552. MIL(Malfunction Indicatin Lamp) turns on when the malfunction lasts till consecutive 2 driving cycles.

DTC Detecting Condition

Item

Detecting Condition

Possible cause

DTC Strategy

•	Detects sensor signal short to low voltage

•	Poor connection

•	Open in power circuit

•	Open or short to ground in signal circuit

•	Faulty P/S pressure sensor

•	Faulty PCM

Enable Conditions

•	Engine works

•	11V ≤ Battery voltage ≤ 16V

Thresh old value

•	Sensor output voltage < 0.25V

Diagnosis Time

•	Continuous

MIL On Condition

•	2 driving cycles

Specification

Pressure(Kgf/cm²)	37.9	41.3	68.8	96.4
Voltage(V)	1	2	3	4

Schematic Diagram

Monitor DTC Status

Check DTC Status

(1)	Connect scantool to Data Link Connector(DLC).

(2)

IG "ON".

(3)	Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.

(4)	Read "DTC Status" parameter.

(5)

Is parameter displayed "Present fault"?

	▶ Go to "Terminal and connector inspection" procedure.
	▶ Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

Terminal And Connector Inspection

1.	Many malfunctions in the electrical system are caused by poor harness and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
	▶ Go to " Power Circuit Inspection " procedure.

Power Circuit Inspection

■ Check voltage

1.	IG Key "OFF".

2.	Disconnect the P/S pressure sensor connector.

3.	IG Key "ON".

Measure the voltage between power terminal of P/S pressure sensor harness connector and chassis ground.

Specification : Approx. 5V

Is the measured voltage within specification ?

	▶ Go to "Signal Circuit Inspection" procedure.
	▶ Repair open or short to ground in harness and go to "Verification of Vehicle Repair" procedure.

Signal Circuit Inspection

■ Check short to ground in harness

1.	IG Key "OFF".

2.	Disconnect P/S pressure sensor connector and PCM connector.

Measure the resistance between signal terminal of P/S pressure sensor harness connector and chassis ground.

Specification : Infinite

Is the measured resistance within specification ?

	▶ Go to "Check open in harness" procedure.
	▶ Repair short to ground in signal harness and go to "Verification of Vehicle Repair" procedure.

■ Check open in harness

1.	IG Key "OFF".

2.	Disconnect P/S pressure sensor connector and PCM connector.

Measure the resistance between signal terminal of P/S pressure sensor harness connector and P/S pressure sensor signal terminal of PCM harness connector.

Specification : Approx. below 1Ω

Is the measured resistance within specification ?

	▶ Go to "Component Inspection" procedure.
	▶ Repair open in signal harness and go to "Verification of Vehicle Repair" procedure.

Component Inspection

P/S pressure sensor inspection

(1)	Key "OFF" and connect the scantool.

(2)	Connect the probe to signal line of P/S pressure sensor and select the oscilloscope in menu.

(3)

Check the waveform with steering handle movement after engine start.

Specification :

Pressure(Kgf/cm²)	Voltage(V)
37.9	1
41.3	2
68.8	3
96.4	4

(4)

Is the measured waveform of P/S pressure sensor normal?

	▶ Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
	▶ Substitute with a known - good P/S pressure sensor and check for proper operation. If the problem is corrected, replace P/S pressure sensor and go to "Verification of Vehicle Repair" procedure.

There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others.

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.

1.	Connect scantool and select "DTC" button.

2.	Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions

3.	Read "DTC Status" parameter

Is parameter displayed "History(Not Present) fault"?

	▶ System performing to specification at this time. Clear the DTC
	▶ Go to the applicable troubleshooting procedure.