Speed display lamp short circuit detection device and method for commercial vehicle

摘要

The present invention detects the disconnection and failure of the external lamp that is lit according to the running speed in the speed display lamp of a commercial vehicle and instructs the driver through the lamp in the room, and cuts the driving power in the event of disconnection or failure of the external lamp It is to protect the driving circuit.;According to an aspect of the present invention, there is provided a speed display device of a commercial vehicle having a speed display lamp and a vehicle speed detection means including an external lamp installed on a roof front portion of a vehicle and an indoor lamp installed on an instrument panel. A vehicle speed input detecting means for detecting a speed change, a control means for executing overall control for driving the speed display lamp by comparing the detected change in the traveling speed with a set reference speed value, and the speed display lamp in accordance with a signal from the control means. And means for detecting the disconnection of the speed display lamp and supplying a predetermined signal corresponding thereto to the control means.