Information Bus: Description and Operation

The Engine Control Module (ECM) and the Transaxle Control Module (TCM) are connected to each other via communication line. The TCM inputs a trouble detection signal to the ECM if any trouble occurs in the automatic transaxle control system.

When some trouble occurs in the automatic transaxle control system, the TCM turns ON the power transistor in it. This causes the ECM 5V voltage to be grounded in the TCM. Therefore, the ECM terminal voltage changes from High to Low. The TCM transmits the information to the ECM by turning on/off its power transistor in this way.