Crankshaft Signal

Terminal "C" provides the ECM with RPM and crankshaft position from a Hall Effect switch. A plate with 3 vanes is mounted on the harmonic balancer. The vanes pass through slots in the crankshaft sensor. As the vanes pass through the slots, a signal is sent to ignition module and from there to the ECM.

The signal from the switch is either high or low and is used to trigger the ignition module for proper engine timing. Both camshaft and crankshaft sensor signals must be seen by the ignition module for a signal to be sent to the ECM.