Faulty Transmission Control Module (TCM)
Transmission Control Module harness is open or shorted
Transmission Control Module circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuits malfunction or which loses power during the current ignition cycle will have a Loss of Communication Diagnostic Trouble Code (DTC) set by other modules that depend on information from that failed module. If any of the CAN circuit are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a Diagnostic Trouble Code will set.