Hall Sending Unit Test (With Knock Control Unit)

Perform Hall sending unit VOLTAGE SUPPLY CHECK (WITH 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.
Connect voltmeter across terminals No. 1 and 2 at rear of 3-wire connector. Remove coil high voltage lead and ground with jumper wire.
Turn ignition switch to "START" position. Voltage should be indicated while starter is actuated.
If voltmeter does not show voltage reading while cranking, replace Hall sending unit. If voltmeter shows voltage while cranking, check for same voltage readings at Hall Ignition Control Unit terminals No. 4 and 6 (2 and 6 on Volkswagen 16-valve).
If readings are not identical, check wire harness from Hall sending unit to knock control unit and from knock control unit to Hall ignition control unit. See Fig 1.

Fig 1: 7-Pin ICU Connector & 15-Pin Knock Sensor Connector

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Fig 2: Positioning Distributor for Hall Effect Testing

Courtesy of AUDI OF AMERICA, INC.