DTC P1380: EBCM DTC Detected Rough Road Data Unstable: 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) receives rough road information from the Electronic Brake Control Module (EBCM) on the serial data circuit. The PCM uses the rough road information in order to enhance the misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from the variations caused by true misfires. The EBCM transmits rough road information based on the inputs from the wheel speed sensors. If the EBCM detects a condition which will not allow the EBCM to properly identify rough road situations while a misfire condition is being detected by the PCM, DTC P1380 will set.