Part 3 of 4

Chart A-3 (Part 3 Of 4):

Chart A-3 Wiring Diagram:

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.


6. The test light to 12 volts simulates a reference signal to the ECM which will result in an injector test light blink with each touch of the test light to terminal "D". It may take up to three touches to get an injector test light flash. CKT 430, the ECM, and the injector driver circuits are all OK.

7. If the crank sensor signal circuit terminal "A" is momentarily jumpered to the ground circuit, terminal "C" and the engine is cranked without turning the ignition switch "OFF," the response should be an injector test light blink. This is a result of the artificial "Sync Signal" being generated. The ignition module will then transmit the fuel control signal while cranking to ECM terminal "BD8" and the ECM will activate the injector driver circuit.

8. Verifies a proper sync signal circuit voltage of 9 to 12 volts and a good ground from the ignition module to terminal "C" of the sensor connector.

9. Determines the reason for incorrect voltage reading was due to a fault in CKT 646, an open in circuit 645 or a faulty ignition module.