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Home >> Volvo >> 1993 >> 240 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Ignition Checks >> BOSCH EZ116K

BOSCH EZ116K

NOTE: ECU terminal identifications are marked on unit or connector.
  1. Ensure ground connections from ignition ECU and power stage to inlet manifold ground are okay. If ground connections are good, disconnect a spark plug wire from spark plug. Connect a test spark plug to disconnected spark plug wire, and ground spark plug. Crank engine, and monitor spark.
  2. A strong Blue/White spark indicates engine or fuel system malfunction. If no or weak spark is present, reconnect spark plug wire to spark plug. Disconnect coil wire from distributor cap, and install test spark plug. Crank engine, and monitor spark. If no spark or weak spark is present, coil or ignition system primary circuit is defective.
  3. If a strong Blue/White spark is present, check ignition rotor, distributor housing and spark plug wires. Replace components as necessary. If previous steps show no defective components, go to next step.
  4. Turn ignition off. Reconnect disconnected components. Ensure all connectors are secure and properly connected. With ignition off, remove panel from lower left dashboard and disconnect ignition ECU connector. Remove dust cover from connector. Ensure all ECU pin connection sleeves are at same height.
  5. Measure voltage at ignition ECU connector terminal No. 5. Voltage should be about 12 volts. If voltage is not present, check circuit between ignition ECU and fuse holder.
  6. Turn ignition on. Open diagnostic connector at left rear of engine compartment, and connect test lead to socket No. 6 (marked on unit). See Figure . Measure voltage at ignition ECU connector terminal No. 1. Voltage should be about 12 volts. Press test button on diagnostic unit. Voltage should now be zero volt. If voltage is not present at control unit or if voltmeter reads 12 volts with button pushed, measure voltage at diagnostic unit connector.
  7. Measure voltage at diagnostic unit connector Blue lead. Voltage should be about 12 volts. Using ohmmeter, check continuity between diagnostic connector Black lead and ground. Continuity should exist.
  8. Turn ignition off. Check continuity between diagnostic test lead and pin No. 8 (under function selector button). Ohmmeter should read infinity. Press button on diagnostic unit. Ohmmeter should now show continuity.
  9. Using ohmmeter, check continuity of diagnostic unit LED. Connect ohmmeter leads to test lead and to pin under LED. Continuity should exist in one direction only.
  10. Turn ignition on. Measure voltage at ignition ECU terminal No. 6 (Blue wire). Voltage should be about 12 volts. Turn ignition off. Check continuity between ignition ECU connector terminals No. 20 (Brown wire) and No. 14 (Black wire). Continuity should be present.
  11. Measure resistance between ground and ignition ECU connector terminal No. 2 (Red/Black wire). See COOLANT TEMPERATURE SENSOR RESISTANCE table under BENDIX REX 1. If reading is not correct, test sensor directly to determine if fault is in sensor or wiring.
  12. Check continuity between ignition ECU connector terminal No. 7 (Orange wire) and ground. Ohmmeter should show continuity. Depress accelerator until throttle switch opens slightly. Ohmmeter reading should increase to infinity. If reading is not correct, measure throttle switch resistance directly to determine if fault is in switch or wiring. Adjust throttle switch if necessary. Refer to the appropriate ADJUSTMENTS article.
  13. Measure voltage at ignition ECU connector terminal No. 8 (Yellow wire). Turn ignition on. Voltage should be about .1 volt. If reading is not correct, check for open circuit between ignition ECU and fuel injection ECU or for fault in fuel injection ECU.
  14. Turn ignition off. Measure resistance between ignition ECU connector terminals No. 10 (Red wire) and No. 23 (Blue wire). Resistance should be 215-265 ohms. Ensure shield is connected to ignition ECU terminal No. 11.
  15. Disconnect knock sensor connector and place a jumper wire between terminals. Check continuity between ignition ECU terminals No. 12 (Black wire) and No. 13 (Green wire). Ohmmeter should show continuity. Ensure resistance to ground is infinity. If resistance is too high (infinity), remove jumper wire and test each wiring lead. If leads are intact, replace knock sensor.
  16. Reconnect knock sensor connector. Reassemble and reconnect ignition ECU connector.
  17. Remove air cleaner assembly. Ensure ignition is off, and disconnect power stage connector. Power stage is located at front of left front fender panel. Remove connector dust cover. Connect multimeter negative (-) lead to ground and positive (+) lead to connector pin No. 4. Turn ignition on, and note voltage reading. Voltage should be about 12 volts.
  18. Leave multimeter attached, and crank starter motor. Voltage should be at least 10.5 volts. If voltage is too low, check battery and charging system. If voltage is not present, check Blue wire from ignition ECU to ignition coil and power stage. Repair or replace as necessary.
  19. Check continuity of power stage ground by connecting multimeter to power stage connector pin No. 2 and ground. Multimeter should show continuity. Check ignition coil resistance. Connect multimeter to power stage connector pins No. 1 and 4. Resistance should be 0.6-1.0 ohm. If resistance is less than 0.6 ohm, check wires for short circuit.
  20. If wires are okay but resistance is still not 0.6-1.0 ohm, connect multimeter between ignition coil terminals No. 1 (Red/White wire) and No. 15 (Blue wire). If resistance is not 0.6-1.0 ohm, install a new ignition coil. If resistance is 0.6-1.0 ohm, check continuity of wires between ignition coil and power stage connector pins No. 1 and 4. Repair or replace as necessary.
  21. Check shield (ground) wire between ignition ECU and power stage. Shield wire is connected to power stage connector pin No. 3 (Gray wire). Repair if necessary. Ensure power stage is receiving signal from ignition ECU. Disconnect wires from ignition coil terminal No. 1. Connect multimeter positive (+) lead to power stage connector pin No. 5 and negative (-) lead to ground.
  22. Crank starter motor, and monitor voltage reading. Voltage should pulsate between 0-2 volts. If voltage is within specification, install a new power stage and recheck circuit. If voltage is very low and/or irregular, check wiring between ignition ECU and crankshaft position sensor. Repair or replace as necessary.
  23. Turn ignition off. If no defects are found in previous steps or if engine still malfunctions after repairs, install a new ignition ECU. Recheck system as necessary.
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