Circuit Description
WARNING: This page is about a different variant/trim than selected.
The transmission control module (TCM) sends vehicle speed data to the engine control module (ECM). The data is sent to the ECM through a communication network called the GM local area network (LAN). Two circuits are used to communicate LAN data between the ECM and TCM. A fault in the LAN will not cause DTC P0864 to set by itself. If a LAN fault occurs, other DTCs set before DTC P0864.
If the ECM receives invalid vehicle speed data from the TCM, DTC P0864 sets.