Abstract: Automobile fog lamp is an important external lighting device for automobile. In the case of badweather, the light penetration of fog lamp is strong, which can improve the visibility of the car and thesurrounding traffic, to warn the drivers and help avoid the occurrence of traffic accidents. However, thecircuit of fog lamp indicator and the control circuit of fog lamp are not necessarily in series , which makesthe fog lamp malfunction and the fog lamp indicator still works normally. Based on the analysis of theworking principle of the automobile fog lamp and the existing hidden danger of the automobile fog lampsystem, this paper improves the branch of the automobile fog lamp and adds a relay to it. When thebranch of the automobile fog lamp malfunctions , the indicator light of the fog lamp will not work , and thiscan solve the problem when the automobile fog lamp system fails to work.

Key words: automobile, control circuit, fog lamp, failure alarm device