The A/C refrigerant pressure sensor signal voltage is more than 4.88 volts for more than 3 seconds.
Action Taken When the DTC Sets
- The ECM stores the DTC information into memory when the diagnostic runs and fails.
- The malfunction indicator lamp (MIL) will not illuminate.
- The ECM disables the A/C compressor clutch.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
- The ECM will report a value of 0 kPa to the HVAC control module.
- The driver information center will display SERVICE A/C SYSTEM.
- The A/C OFF segment will illuminate on the HVAC control module.
Conditions for Clearing the DTC
- A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
- The current DTC will clear when the diagnostic runs and does not fail.
- Use a scan tool in order to clear the diagnostic trouble code.
Diagnostic Aids
| IMPORTANT | Be sure to verify that the ECM engine grounds are secure and clean. |
If DTC P0532 or P0533 cannot be duplicated, reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to set occurs. This may assist in diagnosing the condition.
If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 3: Tests for the proper operation of the circuit in the low voltage range.
- 4: Tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
- 5: Tests for a short to voltage in the 5-volt reference circuit.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 2 | Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the A/C High Side Pressure parameter in the Powertrain Engine Data 2 list. Does the scan tool indicate that the A/C High Side Pressure parameter is within the specified range? | 0.2-4.88 V | Go to Diagnostic Aids | Go to Step 3 |
| 3 | Turn OFF the ignition. Disconnect the A/C refrigerant pressure sensor. Turn ON the ignition, with the engine OFF. With a scan tool, observe the A/C High Side Pressure parameter in the Powertrain Engine Data 2 list. Does the scan tool indicate that the A/C High Side Pressure parameter is less than the specified value? | 0.2 V | Go to Step 4 | Go to Step 10 |
| 4 | Turn OFF the ignition. Connect a 3-amp fused jumper wire between the 5-volt reference circuit and the A/C refrigerant pressure sensor signal circuit of the A/C refrigerant pressure sensor. Turn ON the ignition, with the engine OFF. With a scan tool, observe the A/C High Side Pressure parameter in the Powertrain Engine Data 2 list. Does the scan tool indicate that the A/C High Side Pressure parameter is greater than the specified value? | 4.88 V | Go to Step 5 | Go to Step 8 |
| 5 | Disconnect the fused jumper wire. Measure the voltage between the 5-volt reference circuit and the low reference circuit of the A/C refrigerant pressure sensor. Does the voltage measure less than the specified value? | 5.5 V | Go to Step 6 | Go to Step 7 |
| 6 | Does the voltage measure near the specified value? | 5 V | Go to Step 12 | Go to Step 11 |
| 7 | Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 13 | |
| 8 | Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for the following: An open A high resistance A short to ground Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 9 | |
| 9 | Test the signal circuit of the A/C refrigerant pressure sensor for the following: An open A high resistance A short to ground Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 13 | |
| 10 | Test the signal circuit of the A/C refrigerant pressure sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 13 | |
| 11 | Test the low reference circuit of the A/C refrigerant pressure sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 13 | |
| 12 | Inspect for poor connections at the harness connector of the A/C refrigerant pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 14 | |
| 13 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 15 | |
| 14 | Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement . Did you complete the replacement? | Go to Step 16 | ||
| 15 | Replace the ECM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 16 | ||
| 16 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 2 | System OK | |
DTC P0531, P0532, or P0533
Circuit Description
Ignition voltage is supplied directly to the A/C compressor clutch relay. The engine control module (ECM) controls the relay by grounding the A/C clutch relay control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. The driver has a fault line which is monitored by the ECM. When the ECM is commanding a component ON, the voltage of the control circuit should be near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage. If the fault detection circuit senses a voltage other than what is expected, this DTC will set.
The ECM will monitor the control circuit for the following
- A short to ground
- A short to voltage
- An open circuit
- An open relay coil
- An internally shorted or excessively low resistance relay coil
When the ECM detects any of the above malfunctions, this DTC is set and the affected driver is disabled.
DTC Descriptors
This diagnostic procedure supports the following DTCs
- DTC P0645 Air Conditioning (A/C) Clutch Relay Control Circuit
- DTC P0646 Air Conditioning (A/C) Clutch Relay Control Circuit Low Voltage
- DTC P0647 Air Conditioning (A/C) Clutch Relay Control Circuit High Voltage
Conditions for Running the DTC
- The ignition voltage is between 9-18 volts.
- The engine speed is more than 80 RPM.
- The ECM driver transitions from ON to OFF or from OFF to ON.