Test 11 - Top Dead Center Sensor Testing

TOP DEAD CENTER (TDC) SENSOR TEST


To test the Top Dead Center (TDC) Sensor located in the distributor, proceed as follows.

System Schematic:

OSCILLOSCOPE TESTING PROCEDURE:


1. Connect test leads from the oscilloscope to terminal 4 of the distributor connector and run the engine at idle speed.

Scope Test Waveform--single Rotation Of The Distributor:

Check the waveform and compare it to the diagram shown.

VOLTAGE TESTING PROCEDURE:

1. Connect a voltmeter between terminal 2 and 4 of the top dead center connector.
Terminal 4: Top Dead Center (TDC) signal
Terminal 2: Sensor ground

2. Measure the output voltage of the terminals while cranking the engine.
Standard Approximate Value

Terminal 4: 2.0 - 2.5v

3. If voltmeter readings are not as specified disconnect the distributor connector and check that terminal 3 has near battery voltage with the ignition key in the ON position and that terminal 2 has very low resistance to ground. If power and grounds test properly and there is still no signal output, replace the Top Dead Center (TDC) sensor.
4. If test is as specified, check MPI controller signal output.