一辆东风EQ140型汽车在夜间行驶时,司机将车灯开关扳至3档,侧灯突然变暗发红,位于接线盒内的灯光继电器象蜂鸣器一样嗡嗡发响.按照灯光继电器的设计要求,只有在电路断电器之后的用电设备出现短路时,灯光继电器才能自动将侧灯接通,保证夜间行车的安全.而上述故障出现时,前照灯亮度正常,这说明电路断电器之后并无短路现象.众所周知,灯光继电器线圈L(附图)平时两端的电压相等,线圈中无电流 A Dongfeng EQ140-type car driving at night, the driver will switch the light switch to 3 files, the side light suddenly darken red, located in the junction box light relay buzz buzzer like buzzing.According to the light relay Design requirements, only after the circuit breaker electrical equipment short-circuit, the light relay can automatically turn on the side lights to ensure traffic safety at night. And the above failure occurs, the headlamps brightness is normal, indicating that the circuit breaker After no short circuit phenomenon.As we all know, light relay coil L (with picture) usually the voltage across the same, no current in the coil