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Home >> Volvo >> 1995 >> 940 Base, 4D Sedan, AW71 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Non-Turbo >> Self-Diagnostics - Fuel Injection >> Control Function No. 3 >> Testing Fuel System Components
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Testing Fuel System Components

  1. Turn ignition on. Locate diagnostic unit and remove its cover. Connect selector cable to socket No. 2. Depress push button 3 times. Each time button is depressed, hold it for more than one second and less than 3 seconds. While LED flashes, fuel injectors and idle valve should operate. Check by listening or feeling component when it is activated. If injectors fail to operate and LED flashes, go to step 2). If idle valve fails to operate and LED flashes, go to step 3).
  2. To test fuel injector circuit, connect an ohmmeter between harness side of fuel system ECU connector terminals No. 9 (Blue/Yellow wire) and No. 18 (Gray wire). Resistance should be 4 ohms.
  3. If resistance is 5.3 ohms, one injector or wire to it is faulty. If resistance is 8.0 ohms, 2 injectors or wires to them are faulty. If resistance is 16 ohms, 3 injectors or wires to them are faulty. If resistance is incorrect, remove each injector connector. Each injector connector should have 16 ohms resistance. Repair as required.
  4. To test idle valve circuit, connect an ohmmeter between fuel system ECU connector terminals No. 33 (Red/Black wire) and No. 9 (Blue/Yellow wire). Resistance should be 8 ohms. If resistance is not as specified, check wiring and connections between idle valve and ECU. If wiring is okay, check idle valve. Refer to IDLE CONTROL SYSTEM in the SYSTEM/COMPONENT TESTS article.
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