The ECM/PCM(Engine Control Module) receives pressure signal in the A/C refrigerant high pressure side from the A/C refrigerant pressure sensor. This input indicates how much load the A/C compressor is putting on the engine and is one of the factors used by the ECM/PCM in order to determine the idle air control position for the idle speed. The circuits consist of a 5V reference and a ground, both provided by the ECM/PCM, and a signal from the sensor. The signal is a voltage which is proportional to the A/C pressure from 0 to 5V. Low pressure produces a low voltage signal and high pressure a high-voltage signal.
Checking output signals from A/C pressure sensor under detecting condition, if an signal above 4.668V lasts for more than 10 sec., ECM/PCM sets P0533.
Item | Detecting Condition | Possible cause |
DTC Strategy |
•
Signal check, high | 1. Poor connection 2. Short in signal circuit 3. Open in ground circuit 4. Faulty A/C pressure sensor 5. Faulty ECM/PCM |
EnableConditions |
•
- | |
Threshold value |
•
Sensor output voltage > 4.668V | |
Diagnosis Time |
•
Continuous | |
MIL On Condition |
•
No MIL |
Fig.1) Normal waveforms of A/C pressure sensor during the time from turning on A/C switch to turning off A/C switch.
