DTC P1381: Misfire Detected - No EBCM/Pcm Serial Data: Description
WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) uses the rough road information to enhance the misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from variations caused by true misfires. The Electronic Brake Control Module (EBCM)/Electronic Brake and Traction Control Module (EBTCM) transmits rough road information based on inputs from the wheel speed sensors. If a loss of communication occurs which causes the PCM not to receive rough road information while DTC P0300 is requesting the Malfunction Indicator Light (MIL), DTC P1381 will set.