Cranking Signal: Testing and Inspection

Fig. 027 - Wiring Diagram for Chart C-1B Crank Signal. VIN E, VIN Z:

CHART C-1B

CRANK SIGNAL

4.3L "B/G" SERIES (TBI)

5.0L "F" SERIES (TBI)

Circuit Description:
Crank signal is a 12 volts signal to the ECM during cranking to allow enrichment and cancel diagnostics until engine is running 12 volts is no longer on circuit.

Fig. 026 Chart C-1B Crank Signal:

Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
1. Checks for normal (cranking) voltage to terminal "C9" of ECM. Test light should be "ON" during cranking.
2. Checks to determine if source of blown fuse was a faulty ECM.