Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0532: Air Conditioning (A/C) Pressure Sensor Circuit Low VoltageDTC P0533: Air Conditioning (A/C) Pressure Sensor Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
5-Volt Reference Circuit | P0532 | P0532 | P0533 | -- |
Low Reference Circuit | -- | P0533 | -- | -- |
Signal Circuit | P0532 | P0532 | P0533 | -- |
Circuit/System Description
The engine control module (ECM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. The ECM supplies a 5-volt reference and a low reference to the sensor. Changes in the A/C refrigerant pressure causing the A/C refrigerant pressure sensor signal to the ECM to vary. When the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low. When pressure is high, the ECM commands the cooling fans ON. When pressure is too high or too low, the ECM will not allow the A/C compressor clutch to engage.
Conditions for Running the DTC
| • | The engine is running. |
| • | Any of the conditions for setting the DTC are met for 15 seconds |
Conditions for Setting the DTC
P0532
The ECM detects that the A/C pressure is less than 0 psi.
P0533
The ECM detects that the A/C pressure is more than 428 psi.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM stores the DTC in the Failure Records. |
| • | The A/C compressor clutch is disabled. |
Conditions for Clearing the DTC
| • | The DTC will become history if the ECM no longer detects a failure. |
| • | The history DTC will clear after 40 consecutive ignition cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool. |
Diagnostic Aids
Test the following conditions:
| • | Visually inspect the sensor for contamination or damage. |
| • | Inspect for the following that may affect the sensors accuracy: |
| - | A malfunction within the refrigerant system causing high pressure |
| - | Visually inspect the A/C components and lines for damage. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Automatic HVAC Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, with the engine OFF. Observe the scan tool A/C Refrigerant Pressure parameter. The reading should be between 4.8-5.2 volts and change with A/C pressure.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the A/C refrigerant pressure sensor.
- Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 1 and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.
- Verify the scan tool A/C Refrigerant Pressure parameter is greater than 5.2 volts.
- Install a 3-amp fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 1. Verify the scan tool A/C Refrigerant Pressure parameter is less than 4.8 volt.
- If the circuit tests normal, replace the A/C refrigerant pressure sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If less than the specified range, test the signal circuit terminal for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
- Install a 3-amp fused jumper harness between the 5-volt reference circuit terminal 2 and 5 volts. Install a jumper wire between the low reference terminal 1 and ground.
- Sweep the sensor through the entire range while monitoring the voltage between the signal terminal 3 and the low reference terminal 1. The voltage should vary between 4.8 and 5.2 volts without any spikes or dropouts.
| ⇒ | If the voltage is not within the specified range or is erratic, replace the A/C refrigerant pressure sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
