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Hall Effect Sending Unit Test - 4000S

NOTE: Perform this test only if spark is absent.
  1. Disconnect Hall control unit (in glove box) by pressing wire retaining clip. Set Digital Voltmeter (US 1119 ) on 20-volt scale. Connect voltmeter between terminal No. 4 and 6 at control unit connector. See Fig 1.
  2. Crank engine and check signal from Hall Effect sending unit. Voltmeter should display some voltage. If voltage is displayed, Hall Effect sending unit is okay.
    Fig 1: Audi 4000S Hall Effect Sending Unit Test
    G29163
  3. If no voltage is displayed, turn ignition off and reconnect Hall control unit. Remove connector to Hall Effect sending unit at distributor. Connect voltmeter to outer connector terminals and check voltage supply (from Hall control unit) to sending unit.
  4. Voltmeter should indicate battery voltage. Slide rubber boot away from Hall sending unit connector. Connect voltmeter between battery positive terminal and center wire on connector.
  5. Crank engine and check signal from Hall Effect sending unit. Voltmeter should display an alternating voltage. If not, ignition distributor and/or Hall control unit is defective. Reposition boot.
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