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Home >> Volkswagen >> 1987 >> Quantum Base, Automatic >> Repair and Diagnosis >> Engine Performance >> Ignition System - BOSCH Hall Effect >> Testing >> Hall Effect Sending Unit >> Hall Sending Unit Test (Without Knock Control Unit)
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Hall Sending Unit Test (Without Knock Control Unit)

  1. Perform Hall sending unit VOLTAGE SUPPLY CHECK (WITHOUT KNOCK CONTROL UNIT) before proceeding. Turn ignition off. With 3-wire connector installed at distributor, move protective cover to gain access to rear of connector.
  2. Remove distributor cap, rotor and dust cover. Connect voltmeter across terminals No. 1 and 2 at rear of 3-wire connector. Turn ignition on.
  3. Turn crankshaft until trigger wheel blade blocks Hall sender. See Figure. Voltmeter reading should be greater than 4.0 volts. Turn crankshaft until trigger wheel slot is fully aligned with Hall sending unit. Voltmeter should read 0-.5 volts.
  4. If voltmeter readings do not show a voltage difference while testing, replace Hall sending unit. If voltmeter readings are correct, check for same voltage readings at terminals No. 5 and 6 of the Hall ignition control unit (4 and 6 on models with knock control unit, 2 and 6 on Volkswagen 16-valve). If readings are not identical, check wire harness from Hall sending unit to ignition control unit.
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