Triggering Signals

Two camshaft sensors and a crankshaft sensor provide the triggering signals for the ECM, which uses these signals to control the ignitor(s).

The camshaft sensor contains a pick-up coil. A reluctor is mounted on the camshaft. As the camshaft rotates, a protrusion on the reluctor passes near the pick-up coil. This induces AC voltage in the pick-up coil. ECM interprets this AC voltage signal as TDC of cylinder No. 1.

The crankshaft sensor contains a pick-up coil. A reluctor is mounted on the crankshaft pulley. As the crankshaft rotates, protrusions on the reluctor pass near the pick-up coil. This induces AC voltage in the pick-up coil. The ECM senses the AC voltage, and uses it to determine incremental crankshaft position and engine speed.