Distributor: Description and Operation

Distributor And Connections:

Distributor Exploded View:

PURPOSE
The distributor directs high voltage ignition coil output to the spark plugs in proper sequence (firing order). To accomplish this, a rotor on the driven shaft acts as a rotary contact, directing ignition coil voltage to each spark plug terminal as it turns inside the distributor cap.

OPERATION
The distributor uses photo-diode type crankshaft and camshaft position sensors consisting of a slotted disc that turns with the distributor shaft and a stationary pick-up assembly. As the disc rotates past the pick-up, the slots alternately pass and block photo-diode light transmission. Signals generated are interpreted by the Engine Control Module to determine camshaft position (#1 cylinder TDC) and engine rpm. To calculate ignition timing, the Engine Control Module uses this input together with several others related to vehicle operating conditions. Except for the initial setting, ignition timing is under Engine Control Module control.

CRANK/CAM ANGLE SENSORS
The crank / cam angle sensors are photo-diode types that provide the Engine Control Module with signals regarding engine rpm and #1 cylinder TDC (camshaft position). Together with other inputs, the Engine Control Module calculates ignition timing over the range of vehicle operating conditions.