DTC P1380: EBCM DTC Detected Rough Road Data Unstable: Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, 2002 Chevrolet RV Cutaway, and 2002 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
This Diagnostic Trouble Code (DTC) is used to determine when the Electronic Brake Control Module (EBCM) has lost the ability to provide rough road data to the control module for misfire detection DTC P0300. When the Powertrain Control Module (PCM) detects this condition on the class 2 Serial Data circuit, this Diagnostic Trouble Code (DTC) will be set.