Hall Sending Unit (AUDI 90 & 5000S)
NOTE:
Perform Hall sending unit test only if spark is absent. Ignition coil wire from distributor must always be grounded when checking Hall Effect sending unit. Ensure distributor cap retaining clips do not interfere with trigger wheel unit during testing.
- Remove distributor hames connector from output stage of ignition coil and connect LED tester to terminals No. 2 and 3. Actuate starter and check signal from Hall sender. If LED fluctuates, Hall sender is okay. If not proceed to next step.
- Remove 3-wire connector from distributor unit. Connect voltmeter to the outside teminals. With ignition on, 9 volts minimum should be indicated.
- If voltage is not correct, check Hall Effect harness for open or short. Check voltage supply at terminal No. 4 of ignition control unit, which supplies terminal No. 3 of the distributor connector.
- Turn ignition off. With 3-wire connector installed at distributor, move protective cover to gain access to rear of connector.
- Remove distributor cap, rotor and dust cover. Connect voltmeter across terminals No. 1 and 2 at rear of 3-wire connector.
- Turn crankshaft until trigger wheel blade blocks Hall sender. Turn ignition on. Voltmeter reading should be about 4.0 volts. Turn crankshaft until trigger wheel slot is fully aligned with Hall sending unit. Voltmeter should read 0-.5 volts.
- If voltmeter readings are not to specification, replace Hall sending unit. If voltmeter readings are to specification, check wire harness from Hall sending unit.