P0533 A/C Refrigerant Pressure Sensor ‘A’ Circuit High Input

COMPONENT LOCATION

GENERAL DESCRIPTION

The ECM(Engine Control Module) monitors the A/C Refrigerant Pressure Sensor. The A/C Pressure Sensor is placed in the high pressure line. This signal indicates how much load the A/C compressor is putting on the engine and is one of the factors used by the ECM in order to determine the idle air control position for the idle speed. 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., ECM sets P0533.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Detects sensor signal short to high voltage

1.	Poor connection

2.	Short in signal circuit

3.	Open in ground circuit

4.	Faulty A/C Pressure sensor

5.	Faulty ECM

Enable Conditions

Engine works

Threshold 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(KPa)	101.4	390.9	1723.7	3031.6	3206.1
Voltage(V)	0.5	0.87	2.57	4.24	4.46

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

Fig.1) Normal waveforms of A/C pressure sensor during the time from turning on A/C switch to turning off A/C switch.

MONITOR GDS DATA

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

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.

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 ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminals. 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 “OFF” and disconnect the A/C pressure sensor connector.

IG “ON”

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

Approx. 5V

Is the measured voltage within specification ?

	▶ Go to “Ground Circuit Inspection” procedure.
	▶ Repair open or short to ground in harness and go to “Verification of Vehicle Repair” procedure.

GROUND CIRCUIT INSPECTION

■ Check open in harness

1.	IG “OFF” and disconnect the A/C pressure sensor connector.

IG “ON”

3.	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”)

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 “OFF” and disconnect the A/C pressure sensor connector.

IG “ON”

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

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 “OFF” and disconnect A/C pressure sensor and ECM connector.

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

Infinite

Is the measured resistance within specification?

	▶ Go to “Component Inspection” procedure.
	▶ Repair short to battery in harness

COMPONENT INSPECTION

■ Check A/C pressure sensor

1.	IG “OFF” and connect the GDS.

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

Check the waveform with turning on and off a/c switch after engine start.

Specification :

Pressure(KPa)	101.4	390.9	1723.7	3031.6	3206.1
Voltage(V)	0.5	0.87	2.57	4.24	4.46

Is the measured waveform of A/C pressure sensor normal?

▶ Substitute with a known – good ECM and check for proper operation. If the problem is corrected, replace ECM and go to “Verification of Vehicle Repair” procedure.

There is a memory reset function on GDS that can erase optional parts automatically detected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others.

▶ Substitute with a known – good A/C pressure sensor and check for proper operation. If the problem is corrected, replace A/C pressure sensor

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