Diagnostic Instructions

DTC Descriptor

DTC P0531 00: Air Conditioning (A/C) Refrigerant Pressure Sensor Performance

DTC P0532 00: Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit Low Voltage

DTC P0533 00: Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5 V Reference	P0532 00	P0532 00	--	--
Refrigerant Pressure Sensor Signal	P0532 00	P0532 00	P0533 00	P0531 00
Low Reference	--	P0532 00	--	--

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 V reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the 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 activation of the A/C compressor.

Conditions for Running the DTC

Engine is running.

Conditions for Setting the DTC

P0531 00

The ECM has received an invalid sensor signal.

P0532 00

The ECM detects a short to ground or open at the A/C pressure sensor signal circuit.

P0533 00

The ECM detects a short to voltage at the A/C pressure sensor signal circuit.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Manual HVAC Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B1 A/C Refrigerant Pressure Sensor.
2. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 2 and ground.

⇒	If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace K20 Engine Control Module (ECM).

⇒	If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Test for 4.8-5.2 V between the 5 V reference circuit terminal 2 and the low reference circuit terminal 1

⇒	If less than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace K20 Engine Control Module (ECM).

⇒	If greater than the specified range, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Verify the scan tool A/C High Side Pressure Sensor parameter is less than 0.3 V.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. Install a 3 A fused jumper wire between the following signal circuit terminal 3 and the 5 V reference circuit terminal 2. Verify the scan tool A/C High Side Pressure Sensor parameter is greater than 4.8 V.

⇒	If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

6. If all circuits test normal, replace the B1 A/C Refrigerant Pressure Sensor

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.