Circuit Description
The air conditioning (A/C) refrigerant pressure sensor is used by the engine control module (ECM) to monitor the high side refrigerant pressure. The A/C refrigerant pressure sensor utilizes the following 3 circuits:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A signal circuit |
The ECM monitors the signal circuit voltage. If the A/C high side pressure is high, the signal voltage is high. If the A/C high side pressure is low, the signal voltage is low. The ECM uses the voltage readings to determine the operation of the A/C compressor and the cooling fans. If the ECM detects an excessively high or low signal voltage, a DTC sets.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC P0532 Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit Low Voltage |
| • | DTC P0533 Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit High Voltage |
Conditions for Running the DTC
| • | The engine is running. |
| • | The A/C is requested. |
| • | DTC P0532 and P0532 run continuously once the above condition is met. |
Conditions for Setting the DTC
P0532
| • | The ECM detects that the A/C pressure is less than 0.1 volt. |
| • | The condition exists for more than 10 seconds. |
P0533
| • | The ECM detects that the A/C pressure is more than 4.9 volts. |
| • | The condition exists for more than 10 seconds. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
Conditions for Clearing the MIL/DTC
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Diagnostic Aids
| • | For HVAC system concerns, refer to HVAC Preliminary Checks in Heating, Ventilation and Air Conditioning. |
| • | For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
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 - HVAC Systems - Manual? | -- | Go to Step 2 | |||||||
2 |
Is the voltage within the specified range? | 0.03 - 4.90 V | Go to Step 3 | Go to Step 4 | ||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||
4 |
Is the voltage less than the specified value? | 0.03 V | Go to Step 5 | Go to Step 11 | ||||||
5 |
Is the voltage more than the specified value? | 4.90 V | Go to Step 6 | Go to Step 9 | ||||||
6 |
Is the voltage more than the specified value? | 5.2 V | Go to Step 8 | Go to Step 7 | ||||||
7 |
Is the resistance less than the specified value? | 2 ohms | Go to Step 13 | Go to Step 12 | ||||||
8 |
Important: The 5-volt reference circuits are internally and externally connected at the controller. Other sensors that share the 5-volt reference circuit may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors. Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for a short to voltage. Refer to Circuit Testingand Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | ||||||
9 |
Important: The 5-volt reference circuits are internally and externally connected at the controller. Other sensors that share the 5-volt reference circuit may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors. Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 10 | ||||||
10 | Test the signal circuit of the A/C refrigerant pressure sensor for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | ||||||
11 | Test the signal circuit of the A/C refrigerant pressure sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | ||||||
12 | Test the low reference circuit of the A/C refrigerant pressure sensor for an open or a high resistance. Refer to Circuit Testingand Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | ||||||
13 | Test for an intermittent and for a poor connection at the A/C refrigerant pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairsin Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 | ||||||
14 | Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connectionsand Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | ||||||
15 | Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||
16 | Replace the ECM. Refer to the appropriate procedure:
Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||
17 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 18 | ||||||
18 | Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
