Part 3 of 3

Diagnostic Chart:

Wiring Schematic:

Circuit Description:

If the "Scan tool" did not indicate a engine speed and there is no spark present at the plugs, the problem lies in the electronic ignition system or the power and ground supplies to the module.

The magnetic crankshaft position is used to determine engine crankshaft position sensor much the same way as the pick-up coil did in distributor type systems. The sensor is mounted in the block near a seven slot wheel on the crank shaft. The rotation of the wheel creates a flux change in the sensor which produces a voltage signal. The Ignition Control Module (ICM) then processes this signal and creates the reference pulses needed by the engine control module and the signal triggers the correct coil at the correct time.


Test Description: Numbers below refer to circled numbers on the diagnostic chart.

1. This test will determine if the 12 volt supply and a good ground is available at the ICM.

2. Tests for battery positive voltage in Ignition Feed Circuit to the ICM.

3. Checks for continuity of the crankshaft position sensor and connections.

4. Voltage will vary in this test depending on cranking speed of engine.