Circuit Description

PCM detects engine misfire by detecting variations in crankshaft deceleration between firing strokes. For accurate detection of engine misfire, PCM must be able to distinguish between crankshaft deceleration caused by actual misfire or deceleration caused by rough road conditions.

Electronic Brake Control Module (EBCM) transmits rough road information based on wheel acceleration/deceleration data supplied by the wheel speed sensors. If ABS system detects rough road above a predetermined threshold, information is sent to PCM through serial data circuit. Condition for setting DTC is, PCM is detecting a loss of communications with EBCM/EBTCM for at least 10 seconds.