Ignition System: Description and Operation

C3I IGNITION SYSTEM, 3.8L "A, C, & H" SERIES

The C3I uses a waste spark method of distribution. In this type of system the ignition module triggers the #1/4 coil pair resulting in both #1 and #4 spark plugs firing at the same time. #1 cylinder is on the compression stroke at the same time #4 is on the exhaust stroke, resulting in a lower energy requirement to fire #4 spark plug. This leaves the remainder of the high voltage to be used to fire #1 spark plug.

For timing of spark plug firing, a cam sensor "hall effect" switch is used. The cam sensor sends a signal to the ignition module, when cylinder #1 is on the compression stroke. This signal is used to start the correct sequence of coil firing and to enable sequential fuel injection. The engine will continue to run if the cam signal is lost while running, however, will not restart after shut down and a Code 41 will be stored if the cam signal was lost while running.

The crank sensor sends a signal to the ignition module and then to the ECM for reference RPM and crankshaft position. There are three windows in a disc which is mounted to the harmonic balancer. These windows pass by the sensor and as each window passes, the next coil is triggered.

Verification of "TYPE I" or "TYPE II" is very important, because "TYPE I" diagnostics chart will not work on a "TYPE II" system, or visa versa.

"TYPE I" C3I Ignition System:

"TYPE II" C3I Ignition System: