DTC P1381: Misfire Detected - No EBCM/Pcm Serial Data: Description

WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.

The Powertrain Control Module (PCM) detects engine misfire by detecting variations in the crankshaft deceleration between the firing strokes. For accurate detection of an engine misfire, the PCM must distinguish between a crankshaft deceleration caused by an actual misfire and a deceleration caused by rough road conditions. The ABS Brake System can detect if the vehicle is on a rough road based on the wheel acceleration and deceleration data supplied by the wheel speed sensors. If the ABS system detects a rough road above a predetermined threshold, this information is sent to the PCM via serial data. The PCM can then take the rough road into account when calculating a misfire. Even if serial data communication between the ABS System and the PCM is malfunctioning and the PCM cannot receive the rough road data, the misfire diagnostic continues to run. If a misfire DTC sets, this additional DTC also sets, indicating that the rough road data was not available during the misfire calculation due to a serial data malfunction.