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

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

Rough roads cause torque on the tires that is transmitted to the powertrain. This condition slows down the crankshaft, giving the appearance of a misfire. The Electronic Brake and Traction Control Module (EBTCM) determines rough road surfaces using input from the wheel speed sensors. The EBTCM then sends the rough road data to the PCM via class 2 serial data. The Powertrain Control Module (PCM) uses the rough road data in order to enhance the misfire diagnostic. The data allows the PCM to distinguish the crankshaft speed variations caused by rough road surfaces from those caused by true misfires. If a loss of communication occurs that causes the PCM not to receive the rough road information when a misfire condition is requesting the Malfunction Indicator Light (MIL), DTC P1381 will set.