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DTC 225: A/C Pressure Sensor

  1. If fault is permanent and signal is too high, go to next step. If fault is permanent and signal is too low, go to step 6). If fault is intermittent and signal is too high, go to step 11). If fault is intermittent and signal is too low, go to step 12). If fault is permanent and signal is faulty, replace A/C pressure sensor. If fault is intermittent and signal is faulty, check wiring for an intermittent open circuit.
  2. Turn ignition off. Wait about 2 minutes. Disconnect A/C pressure sensor. Connect an ohmmeter between A/C pressure sensor connector terminal No. 1 and ground. If ohmmeter reads about zero ohms, go to step 4). If ohmmeter does not read about zero ohms, go to next step.
  3. Turn ignition off. Disconnect A/C pressure sensor connector. Check ECM connector for oxidation and poor terminal contact. Repair as necessary. Reconnect ECM connector. Connect an ohmmeter between A/C pressure sensor connector terminal No. 1 and ground. If ohmmeter reads about zero ohms, go to next step. If ohmmeter does not read about zero ohms, check wiring between A/C pressure sensor connector terminal No. 1 and ECM connector terminal B28 for an open circuit.
  4. Turn ignition on. Disconnect A/C pressure sensor connector. Connect a voltmeter between A/C pressure sensor connector terminal No. 2 and ground. If voltmeter reads about zero volts, go to next step. If voltmeter does not read about zero volts, check wiring between A/C pressure sensor connector terminal No. 2 and ECM connector terminal B9 for a short to voltage.
  5. Turn ignition off. Connect ohmmeter between A/C pressure sensor connector terminal No. 2 and ground. If ohmmeter does not read about 10 k/ohms, check wiring between A/C pressure sensor terminal No. 2 and ECM connector terminal B9 for an open circuit. If ohmmeter reads about 10 k/ohms, reconnect A/C pressure sensor. Start engine and idle for 15 seconds. Turn A/C and blower on. If scan tool indicates voltage increases when A/C compressor starts, DTC was caused by poor terminal contact. If scan tool does not indicate voltage increase, replace A/C pressure sensor.
  6. If fault is permanent and signal is too low, turn ignition off. Disconnect A/C pressure sensor. Turn ignition on. Connect voltmeter between A/C pressure sensor connector terminal No. 3 and ground. If voltmeter reads less than 5 volts, go to step 8). If voltmeter reads greater than 5 volts, ensure A/C pressure sensor voltage feed wire is connected inside ECM to accelerometer voltage feed. A problem with one wire will affect both. Repair as necessary. If voltmeter reads about 5 volts, check resistance between A/C pressure sensor terminal No. 2 and ground. If ohmmeter reads about 10 k/ohms, go to next step. If ohmmeter does not read about 10 k/ohms, check wiring for a short to ground.
  7. Reconnect A/C pressure sensor. Start and idle engine. Turn A/C and blower on. If scan tool indicates voltage increases when A/C compressor starts, DTC was caused by poor terminal contact. If scan tool does not indicate voltage increase, replace A/C pressure sensor.
  8. Turn ignition off. Disconnect A/C pressure sensor connector. Wait 2 minutes. Connect ohmmeter between A/C pressure sensor connector terminal No. 3 and ground. If ohmmeter reads lower than .2-1.5 k/ohms, go to next step. If ohmmeter reads higher than .2-1.5 k/ohms, check connectors for poor terminal contact. Repair as necessary and repeat test. If reading is still incorrect, check wiring between A/C pressure sensor terminal No. 3 and ECM connector terminal B29 for an open circuit.
  9. Connect ohmmeter between A/C pressure sensor connector terminal No. 3 and ground. If ohmmeter reads .2-1.5 k/ohms, replace accelerometer. If ohmmeter does not read .2-1.5 k/ohms, ensure A/C pressure sensor voltage feed wire is connected inside ECM to accelerometer voltage feeds. A problem with one wire will affect both components. Repair as necessary.
  10. If fault is intermittent and signal is too high, check A/C pressure sensor and ECM connectors for loose connection or contact resistance. Check wiring between A/C pressure sensor connector terminal No. 2 and ECM connector terminal B9 for an intermittent open circuit. Also check wiring between A/C pressure sensor connector terminal No. 1 and ECM connector terminal B28 for an intermittent open circuit or short circuit to ground.
  11. If fault is intermittent and signal is too low, check for an intermittent open circuit or short circuit to ground in wiring between A/C pressure sensor connector terminal No. 3 and ECM connector terminal B29, and wiring between A/C pressure sensor terminal No. 2 and ECM connector terminal B9. Repair as necessary.
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