• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
5-Volt Reference | P0532 | P0532 | -- | -- |
A/C Refrigerant Pressure Sensor Signal | P0532 | P0532 | P0533 | -- |
Low Reference | -- | P0533 | -- | -- |
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 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.
• | Engine is running. |
• | Any of the conditions for setting the DTC are met for 15 seconds. |
• | Battery voltage is between 11-18 volts. |
• | The ECM detects that the A/C pressure is less than 1 psi (0.01 volt) sets DTC P0532. |
• | The ECM detects that the A/C pressure is more than 428 psi (4.92 volts) sets DTC P0533. |
• | The ECM will not illuminate the malfunction indicator lamp (MIL). |
• | The ECM stores the Failure Records. |
• | The A/C compressor clutch is disabled. |
• | 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. |
A malfunction within the refrigerant system causing high pressure can cause this DTC to set.
Ignition ON, observe the scan tool A/C Refrigerant 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.
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.
⇒ | 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 greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM. |
⇒ | 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. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for the ECM replacement, setup, and programming |