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Home >> Volvo >> 1991 >> 240 SE, AW70L >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Self-Diagnostics - Fuel Injection >> Control Function No. 2 >> Activating Circuit Breakers

Activating Circuit Breakers

  1. Turn ignition on. Locate diagnostic unit, and remove its cover. Connect selector cable to socket No. 2. Turn throttle control at throttle body to full-load position. Depress push button twice. Each time the button is depressed, it should be held for more than 1 second and less than 3 seconds. The Red LED should flash.
  2. Release throttle control. If flash series 3-3-3 comes up, the throttle switch works correctly in full-load position. If LED continues to flash rapidly, check throttle switch setting. See procedures in ADJUSTMENTS article in the ENGINE PERFORMANCE Section and proceed to next step.
  3. Connect an ohmmeter between terminal No. 3 (Yellow/White wire on 240 Series; Orange wire on all others) of fuel system ECU and ground. Resistance should be infinite with throttle switch closed. Depress gas pedal slightly. Resistance should be zero ohms. If resistance is not as specified, check wiring from ECU to throttle switch.
  4. Turn throttle control slightly and observe Red LED. If LED turns off and then flashes 3-3-2 code, the throttle switch is working properly in idle position. If LED does not flash as described, repeat step 3).
  5. Start engine and check RPM signal from ignition system ECU to fuel system ECU. If LED turns off and then flashes 3-3-1 code, RPM signal is correct. If engine won't start, run the starter until the LED turns off and proceed to next step. If the LED continues to flash, check ignition system and see DIAGNOSTIC UNIT LED DOES NOT FLASH  in this article.
    NOTE: Steps 6-9 are for A/C equipped vehicles and steps 10-11 are for A/T equipped vehicles.
  6. Check on/off function of A/C compressor. Put A/C control in ON position. If LED turns off and then flashes 1-1-4 code, A/C switch is okay. Proceed to step 8). If LED continues to flash, proceed to next step.
  7. Connect an ohmmeter between terminal No. 15 (Gray/Red wire on 240 Series; Green/Yellow wire on all others) of fuel system ECU and ground. On 240 Series, resistance should be 1000 ohms with A/C off and 10 ohms with A/C on. On all others, resistance should range from infinity with A/C off and 35 ohms with A/C on. If resistance is not as specified, check wiring and connections.
  8. Turn ignition off. The LED should flash rapidly prior to A/C compressor turning on. When the compressor turns on, the LED should turn off and then flash 1-3-4. If LED continues to flash, proceed to next step.
  9. Connect an ohmmeter between terminal No. 15 (Green/Yellow wire) of fuel system ECU and ground. Resistance should be 35 ohms with A/C switch on. If resistance is not as specified, check wiring and connections.
  10. This step will test idle speed compensation on A/T equipped vehicles. Depress brake pedal and place gear selector in DRIVE position and then NEUTRAL position. Observe LED while shifting. A code 1-2-4 should flash and test is complete. If LED continues to flash rapidly, proceed to next step.
  11. Put transmission gear selector in NEUTRAL position. Connect an ohmmeter between terminal No. 30 (Blue/Yellow wire on 240 Series; Pink wire on all others) of fuel system ECU and ground. Resistance should be zero ohm in NEUTRAL position and infinity in DRIVE position. If resistance is not as specified, check wiring, connections and gear selector switch.
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