GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 DTS 🢒 HVAC 🢒 HVAC - Automatic 🢒 DTC P0532 or P0533

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 Refrigerant Pressure Sensor Circuit Low Voltage

DTC P0533: Air Conditioning A/C Refrigerant Pressure Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

5-Volt Reference

P0532

P0532

P0533

A/C Refrigerant Pressure Sensor Signal

P0532

P0533

P0532

Low Reference

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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 cause the A/C refrigerant pressure sensor signal to the ECM to vary. When the pressure is low, the signal voltage is low. When the 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.

Conditions for Setting the DTC
    • The ECM detects that the A/C pressure is less than 1 psi (0.01 volt).
    • The ECM detects that the A/C pressure is greater than 425 psi (4.90 volts).

Action Taken When the DTC Sets
    • The ECM will not illuminate the malfunction indicator lamp (MIL).
    • The ECM stores the failure records.
    • The A/C compressor clutch is disabled.

Conditions for Clearing the DTC
    • The history DTC will clear after 40 consecutive ignition cycles have occurred without a malfunction.
    • The DTC will become history if the ECM no longer detects a failure.

Diagnostic Aids

A malfunction within the refrigerant system causing high pressure can cause this DTC to set.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool A/C Pressure Sensor parameter. The reading should be between 0.1 volts (1 psi) and 4.90 volts (425 psi) and change with A/C refrigerant pressure changes.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the A/C refrigerant pressure sensor.
  2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal A and ground.
    3. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal B and ground.
    4. ⇒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.
  4. Verify the scan tool A/C High Side Pressure Sensor parameter is less than 0.1 volts (1 psi).
    5. ⇒If greater than the specified range, test the signal circuit terminal C for a short to voltage. If the circuit tests normal, replace the ECM.
  5. Install a 3A fused jumper wire between the signal circuit terminal C and the 5-volt reference circuit terminal B. Verify the scan tool A/C High Side Pressure Sensor parameter is greater than 4.90 volts (425 psi).
    6. ⇒If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  6. If all circuits test normal, test or replace the A/C refrigerant pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement
    •  Control Module References for the ECM replacement, setup, and programming