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Control Unit & Pick-Up Coil Check

  1. Disconnect high tension coil wire from distributor cap. Using insulated pliers, hold end of coil wire 1/2" from engine block.
  2. Turn the ignition switch to "ON" position and disconnect 4-wire connector from control unit. Watch for spark as connector is disconnected. If spark occurs, proceed to step 3). If no spark occurs, proceed to step 6).
  3. Turn ignition switch to "OFF" position and connect an ohmmeter between the Orange and Violet wire terminals "D3" and "D5" of MCU harness connector. Ohmmeter reading should be 400-800 ohms. If reading is correct, proceed to step 8). If not, proceed to step 4).
  4. Disconnect and reconnect 3-wire connector at distributor. If ohmmeter reading is now correct, proceed to step 8). If reading is still not correct, proceed to step 5).
  5. Disconnect 3-wire connector at the distributor and connect ohmmeter leads between the Orange and Violet wire terminals "B2" and "B3" of distributor connector. If reading is now 400-800 ohms, repair or replace harness between 3-wire and 4-wire connectors. If reading is still not to specifications, replace pick-up coil assembly in distributor.
  6. Connect ohmmeter leads to battery negative terminal (ground) and Black wire terminal "D1" in harness connector. Ohmmeter reading should be nearly 0 (less than .002 ohms).
  7. If ohmmeter reading is okay, proceed to step 3). If reading is above .002 ohms, check for bad ground (ground cable, distributor-to-engine block or ground screw in distributor-to-Black wire terminal "D1").
  8. With voltmeter connected to harness side of MCU J2 connector Orange and Violet wire terminals "D3" and "D5", crank engine. Voltmeter reading should fluctuate. If not, check for defective trigger wheel, distributor shaft not turning, or missing trigger wheel retaining pin.
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