Circuit Description

Modules that are connected to the CAN serial data circuits monitor each other for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. the modules have prerecorded information about messages that are exchanged on the serial data circuits. The supervised and periodic messages are used by the receiving module as an availability, and state of health indicator from the transmitting module. If the engine control module (ECM) detects a message that indicates a loss of communication, invalid or corrupted serial data, or an active malfunction in the transmission control module (TCM), that requires ECM intervention, DTC P0701 sets.