DTC P1381: Misfire Detected - No Communication With Brake Control Module: Description
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 Pontiac Grand Prix, 2002 Pontiac Bonneville, 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, and 2002 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
Powertrain Control Module (PCM) receives rough road information from Electronic Brake Control Module (EBCM) on serial data circuit. PCM uses rough road information to enhance misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from variations caused by true misfires. EBCM transmits rough road information based on inputs from wheel speed sensors. DTC sets when a loss of communication occurs which causes PCM not to receive rough road information while DTC P0300 is requesting MIL.