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.
Checking output signals from A/C pressure sensor under detecting condition, if an signal below 0.25V lasts for more than 10 sec., PCM sets P0532.
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 A/C pressure sensor ● Faulty PCM | |
Enable Conditions | ● Engine running | ||
Thresh old value | ● Sensor output voltage〈 0.25V | ||
Diagnosis Time | ● Continuous (More than 10 seconds failure for every 20 seconds test ) | ||
MIL On Condition | ● DTC only (NO MIL ON) |
Pressure(psi) | 14.7 | 128.5 | 242.3 | 356.1 | 469.9 | |
Voltage(V) | 0.5 | 1.5 | 2.5 | 3.5 | 4.5 |
Check DTC Status
Connect scantool to Data Link Connector(DLC).
IG "ON".
Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.
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 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.
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.
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.
IG Key "OFF".
Disconnect the A/C pressure sensor connector.
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 "Signal Circuit Inspection" procedure.
▶ Repair open or short to ground in harness and go to "Verification of Vehicle Repair" procedure.
IG Key "OFF".
Disconnect A/C pressure sensor and PCM connector.
Measure the resistance between signal terminal of A/C 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 harness and go to "Verification of Vehicle Repair" procedure.
IG Key "OFF".
Disconnect A/C pressure sensor and PCM connector.
Measure the resistance between signal terminal of A/C pressure sensor harness connector and A/C 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 harness and go to "Verification of Vehicle Repair" procedure.
Check A/C pressure sensor
IG Key "OFF" and connect the scantool.
Connect the probe to A/C pressure sensor signal and select the oscilloscope in the menu.
Check the waveform with acceleration and deceleration after engine start.
Pressure(psi) | 14.7 | 128.5 | 242.3 | 356.1 | 469.9 | |
Voltage(V) | 0.5 | 1.5 | 2.5 | 3.5 | 4.5 |
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
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "DTC" button.
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
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.