Fuel System > Engine Control System > P0533 A/C Refrigerant Pressure Sensor \

Commponent Location

General Description

The PCM(Engine Control Module) receives pressure signal in the A/C refrigerant high pressure side from the A/C refrigerant pressure sensor. This input indicates how much load the A/C compressor is putting on the engine and is one of the factors used by the PCM in order to determine the idle air control position for the idle speed. The circuits consist of a 5V reference and a ground, both provided by the PCM, and a signal from the sensor. The signal is a voltage which is proportional to the A/C pressure from 0 to 5V. Low pressure produces a low voltage signal and high pressure a high-voltage signal.

DTC Description

Checking output signals from A/C pressure sensor under detecting condition, if an signal above 4.65V lasts for more than 10 sec., PCM sets P0533.

DTC Detecting Condition

Item

Detecting Condition

Possible cause

DTC Strategy

•	Detects sensor signal short to high voltage

•	Poor connection

•	Short battery in signal circuit

•	Open in ground circuit

•	Faulty A/C pressure sensor

•	Faulty PCM

Enable Conditions

•	Engine running

Thresh old value

•	Sensor output voltage > 4.65V

Diagnosis Time

•	Continuous (More than 10 seconds failure for every 20 seconds test)

MIL On Condition

•	DTC only (NO MIL ON)

Specification

Pressure(psi)	14.7	128.5	242.3	356.1	469.9
Voltage(V)	0.5	1.5	2.5	3.5	4.5

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 A/C pressure sensor connector.

3.	IG Key "ON".

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

Specification : Approx. 5V

Is the measured voltage within specification ?

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

Ground Circuit Inspection

■ Check open in harness

1.	IG Key "OFF".

2.	Disconnect the A/C pressure sensor connector.

3.	IG Key "ON".

4.	Measure the voltage between power terminal of A/C pressure sensor harness connector and chassis ground.(Measurement "A")

Measure the voltage between power and ground terminals of A/C pressure sensor harness connector.(Measurement "B")

Specification : The Difference between "A" and "B" is below 200mV.

Is the measured voltage within specification ?

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

SIGNAL CIRCUIT INSPECTION

■ Check voltage

1.	IG Key "OFF".

2.	Disconnect the A/C pressure sensor connector.

3.	IG Key "ON".

Measure the voltage between signal terminal of A/C pressure sensor harness connector and chassis ground.

Specification : Approx. 0V

Is the measured voltage within specification ?

	▶ Go to "Component Inspection" procedure.
	▶ Go to "Check short to battery in harness" procedure.

■ Check short to battery in harness

1.	IG Key "OFF".

2.	Disconnect A/C pressure sensor connector and PCM connector.

Measure the resistance between signal and power terminals of A/C pressure sensor harness connector.

Specification : Infinite

Is the measured resistance within specification ?

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

Component Inspection

Check A/C pressure sensor

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

(2)	Connect the probe to A/C pressure sensor signal and select the oscilloscope in the menu.

(3)

Check the waveform with acceleration and deceleration after engine start.

Specification :

Pressure(psi)	Voltage(V)
14.7	0.5
128.5	1.5
242.3	2.5
356.1	3.5
469.9	4.5

(4)

Is the measured waveform of A/C 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 A/C pressure sensor and check for proper operation. If the problem is corrected, replace A/C 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 before reusing the PCM

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.