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Home >> Volvo >> 1998 >> S70 Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> DTC P0530/EFI 225, DTC P0531/EFI 225, DTC P0532/EFI 225 & DTC P0533/EFI 225 (Turbo) >> Diagnosis (Signal Too Low, Permanent Fault)

Diagnosis (Signal Too Low, Permanent Fault)

  1. Checking power cable Turn ignition off. Disconnect the air conditioning (A/C) pressure sensor. Turn ignition on. Connect a voltmeter between air conditioning (A/C) pressure sensor connector 3 and ground. The voltmeter should read 5V. If reading is OK, go to step  3. If value is lower, go to step  5. If value is higher, go to step  2.
    2. NOTE: Atmospheric pressure sensor is used on turbocharged engines.
  2. Checking for short circuit. Air conditioning (A/C) pressure sensor power cable is connected inside the ECM to the fuel tank pressure sensor, atmospheric pressure sensor and accelerometer power cables. If anything happens to any of these cables all four will be affected. Check cables for a short circuit to supply voltage between:
    • Accelerometer terminal 1 and ECM terminal No. B1
    • Air conditioning (A/C) pressure sensor terminal 3 and ECM terminal No. B29
    • Atmospheric pressure sensor terminal 1 and ECM terminal No. B29
    • Tank pressure sensor terminal 1 and ECM terminal No. B15
    After repairs, go to step  11.
  3. Checking signal cable resistance. Turn ignition off. Air conditioning (A/C) pressure sensor disconnected. Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 2 and ground. The ohmmeter should read approximately 10,000 ohms. If reading is OK, go to step  4. If reading is NOT OK, the cause of the DTC has been loose connections in the air conditioning (A/C) pressure sensor connector. Check connector for contact resistance and oxidation and remedy. After repairs, go to step  11.
  4. Checking the air conditioning (A/C) pressure sensor. Turn ignition off. Connect air conditioning (A/C) pressure sensor. Start the engine and idle it. Turn air conditioning (A/C) switch on. Turn blower fan on. Select Volvo Scan Tool, or aftermarket scan tool, to read off the value of the air conditioning (A/C) pressure sensor signal. Voltage should increase when the air conditioning (A/C) compressor starts. If reading is NOT OK, try a new A/C pressure sensor. Go to step  11. If reading is OK, the cause of the DTC has been loose connections in the air conditioning (A/C) pressure sensor connector. Check connector for contact resistance and oxidation and remedy. Go to step  11.
  5. Checking power cable resistance to ground. Turn ignition off. Air conditioning (A/C) pressure sensor disconnected. Wait for approximately 150 seconds (cars with immobilizer 245 seconds). Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground. The ohmmeter should read approximately 200-1500 ohms. If value is lower, go to step  6. If value is higher, go to step  10.
  6. Checking accelerometer. Turn ignition off. Air conditioning (A/C) pressure sensor disconnected. Disconnect accelerometer. Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground. The ohmmeter should read about 200-1500 ohms. If reading is OK, try a new accelerometer. Go to step  11. If reading is NOT OK, go to step  7.
    7. NOTE: Atmospheric pressure sensor is used on turbocharged engines. Models with EVAP leak diagnostic are equipped with a fuel tank pressure sensor.
  7. Checking atmospheric pressure sensor. Turn ignition off. Air conditioning (A/C) pressure sensor and accelerometer disconnected. Disconnect atmospheric pressure sensor. Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground. The ohmmeter should read approximately 200-1500 ohms. If reading is OK, try a new atmospheric pressure sensor. Go to step  11. If reading is not OK:
    • Models With EVAP leak diagnostic: Go to step  8.
    • Models Without EVAP leak diagnostic: Go to step  9.
    8. NOTE: Atmospheric pressure sensor is used on turbocharged engines.
  8. Checking fuel tank pressure sensor. Turn ignition off. Air conditioning (A/C) pressure sensor, accelerometer and atmospheric pressure sensor disconnected. Disconnect fuel tank pressure sensor. Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground. The ohmmeter should read approximately 200-1500 ohms. If reading is OK, try a new fuel tank pressure sensor. Go to step  11. If reading is NOT OK, go to  9.
  9. Checking for a short-circuit. The air conditioning (A/C) pressure sensor power cable is connected inside the ECM to the fuel tank pressure sensor, atmospheric pressure sensor and accelerometer power cables. If anything happens to any of these cables all four will be affected. Check cables for a short circuit to ground between:
    • Accelerometer terminal 1 and ECM terminal No. B1
    • Air conditioning (A/C) pressure sensor terminal 3 and ECM terminal No. B29
    • Atmospheric pressure sensor terminal 1 and ECM terminal No. B29
    • Tank pressure sensor terminal 1 and ECM terminal No. B15
    Go to step  11.
  10. Checking ECM connector. Turn ignition off. Air conditioning (A/C) pressure sensor disconnected. Check ECM connector for contact resistance and oxidation and remedy. Check wiring and terminals. With ECM connected, connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground. The ohmmeter should read approximately 200-1500 ohms. If reading is OK, DTC has been caused by loose connections in the ECM connector. Go to step  11. If reading is NOT OK, check wire between air conditioning (A/C) pressure sensor terminal 3 and ECM terminal No. B29 for an open-circuit. Go to step  11.
  11. Verification. After carrying out the repair, check that the fault has been remedied as follows: Turn ignition off. Air conditioning (A/C) pressure sensor and ECM connected. Start the engine and idle it. Air conditioning (A/C) switch on. Blower fan on. Wait until the air conditioning (A/C) compressor has started. Select Volvo Scan Tool, or aftermarket scan tool, to read off DTCs. If EFI-225 is stored it should have intermittent status.
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