DTC P1380: EBTCM DTC Detected Rough Road Data Unusable: 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 PCM uses the rough road data in order to enhance the misfire diagnostic. The data allows the PCM in order to distinguish the crankshaft speed variations caused by rough road surfaces from variations caused by true misfires. If the EBTCM is unable to identify rough road conditions when the PCM detects a misfire condition, DTC P1380 will set.