Test 3 - Power Transistor Testing

System Schematic:

To test the Power Transistor assembly, located on the intake manifold, using an analog type circuit tester proceed as follows.

Component Test:

1. Disconnect the power transistor connector.
2. Connect a power supply of 1.5v (one dry cell) between power transistor terminals 3 (-) and 2 (+).
3. Check for continuity between terminals 1 (+) and 3 (-). There should be continuity.
4. Remove power from terminals 3 and 2.
5. Check for continuity between terminals 1 (+) and 3 (-). There should not be continuity.
6. Connect a power supply of 1.5v (one dry cell) between power transistor terminals 3 (-) and 5 (+).
7. Check for continuity between terminals 6 (+) and 3 (-). There should be continuity.
8. Remove power from terminals 3 and 6.
9. Check for continuity between terminals 6 (+) and 3 (-). There should not be continuity.

If the Power Transistor assembly fails any of these tests, replace it.


OSCILLOSCOPE TEST

Power Transistor Control Signal Scope Pattern:

Power transistor control signal test.
1. Crank or run engine.
2. Connect the scope probe to connector terminals # 2 & # 5 (one side at a time) shown in the System Schematic diagram and compare each signal to the pattern shown. If no signal is present check for an open/short in the wiring between MPI computer and power transistor. If wiring is not good repair as necessary and retest. If wiring is good check top dead center sensor.