Note. For circuit reference, see WIRING DIAGRAMS article.
Circuit Description
The PCM uses information from Crankshaft Position (CKP) sensors and Camshaft Position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, PCM is able to detect individual misfire events. A misfire rate that is high enough can cause three-way catalytic converter damage. The MIL will flash on and off when the conditions for catalytic converter damage are present.