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P0532






P0532-A/C PRESSURE SENSOR CIRCUIT LOW

For a complete wiring diagram, refer to the Wiring Information.





Theory of Operation

The Powertrain Control Module (PCM) receives a signal requesting the A/C Compressor to be turned on from the HVAC. When the PCM receives this request it grounds the control side of the relay. The Powertrain Control Module (PCM) receives feedback from the A/C Pressure Transducer to monitor the pressure in the high side of the A/C refrigerant system. The A/C Pressure Transducer connects to a fitting on the A/C discharge line and its internal resistance changes in response to the pressure in the system. The PCM provides a 5-Volt reference signal and a sensor ground to the A/C Pressure Transducer, then monitors the output voltage of the transducer on the sensor signal circuit to determine refrigerant pressure. The PCM is programmed to respond to this and other sensor inputs and control the operation of the A/C Clutch and the Radiator Cooling Fan to help optimize A/C system performance and to protect the A/C system components from damage. The PCM will request disengagement of the A/C Clutch when high side pressure rises above the calibrated maximum limit and re-engage the clutch when high side pressure drops back below the limit. The PCM will also disengage the A/C Clutch if the high side pressure drops below the calibrated minimum limit and will re-engage the clutch when the high side pressure rises back above the limit. When the refrigerant pressure rises above a calibrated pressure specific to the PCM, the PCM will actuate the cooling fan.

- When Monitored:
With the ignition on.

- Set Condition:
The A/C pressure transducer signal voltage received by the PCM is below the minimum acceptable value. One Trip Fault.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. ACTIVE DTC

NOTE: Diagnose and repair any system voltage or 5-Volt reference DTCs before continuing with this test.

NOTE: Make sure the A/C refrigerant System is properly charged. .

1. Start the engine and allow it to reach normal operating temperature.

WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in possible serious or fatal injury.

2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECK THE (C818) 5-VOLT SUPPLY CIRCUIT VOLTAGE
1. Turn the ignition off.
2. Disconnect the A/C Pressure Transducer harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (C818) 5-Volt Supply circuit at the A/C Pressure Transducer harness connector.

Is the voltage above 4.8 volts?

Yes

- Go To 6

No

- Go To 3

3. CHECK THE (C818) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition on.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between ground and the (C818) 5-Volt Supply circuit at the A/C Pressure Transducer harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 4

No

- Repair the (C818)5-Volt Supply circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. CHECK FOR THE (C818) 5-VOLT SUPPLY CIRCUIT SHORTED TO THE (C918) SENSOR GROUND CIRCUIT
1. Measure the resistance between the (C818) 5-Volt Supply circuit and the Sensor Ground circuit at the A/C Pressure Transducer harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 5

No

- Repair the short between the (C818) 5-Volt Supply circuit and the (C918) Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. CHECK THE (C818) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (C818) 5-Volt Supply circuit between the A/C Pressure Transducer harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 10

No

- Repair the (C818) 5-Volt Supply circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. CHECK THE (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between ground and the A/C Pressure Sensor Signal circuit in the A/C Pressure Transducer harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 7

No

- Repair the (C18) A/C Pressure Sensor Signal circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

7. CHECK FOR THE (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO THE (C918) SENSOR GROUND CIRCUIT
1. Measure the resistance between the A/C Pressure Sensor Signal circuit and the Sensor Ground circuit in the A/C Pressure Transducer harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 8

No

- Repair the A/C Pressure Sensor Signal circuit for a short to the Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

8. (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (C18) A/C Pressure Sensor Signal circuit between the A/C Pressure Transducer harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 9

No

- Repair the (C18) A/C Pressure Sensor Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

9. AC PRESSURE TRANSDUCER
1. Turn the ignition off.
2. Reconnect the PCM C1 harness connector.
3. Connect a jumper between the (C818) 5-Volt Supply circuit and the A/C Pressure Sensor Signal circuit at the A/C Pressure Transducer harness connector.
4. Turn the ignition on.
5. With the scan tool, read the AC Pressure Transducer signal voltage.

Is the voltage above 4.8 volts with the jumper wire in place?

Yes

- Replace the A/C Pressure Transducer. .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 10

10. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the A/C Pressure Transducer and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM). .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

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