Abstract: A multiplex transmission system for vehicles having a plurality of multiplex nodes connected to a transmission path in order to communicate information therebetween for controlling a vehicle. Each of the multiplex nodes a priority code which indicates a priority of the signals to be transmitted with the data when a plurality of multiplex nodes concurrently transmit data and accordingly the signals therefrom collide with each other. The priority data includes a first priority which attaches importance to high responsiveness for the engine and a second priority which attaches importance to safety. A detector is provided for detecting the traffic condition in the multiplex transmission path. A priority changer is provided for changing the priority respectively in accordance with the traffic condition, so that proper control of both response and safety can be reconciled.

Abstract: An engine control system for a vehicle having an automatic transmission in which the gear-shifting is automatically done on the basis of a predetermined shift pattern comprises an engine output control system for controlling the output power of the engine, a detecting system which detects actual shifting action of the gear train mechanism of the automatic transmission, and an engine control unit which receives a signal from the detecting system and delivers to the engine output control system a control signal for temporarily lowering the engine output power while the actual shifting action of the gear mechanism is in progress.