Fault diagnosis: the X431 terminal is used to measure the fault of the 30 terminal line, and the engine fault lights and ABS lights on the instrument are lighted at the same time, and the other instructions are normal. The charging voltage of the generator is normal at idle speed. Ask the owner that the fault occurred after a period of time. To this end, we simulate its work situation, continuous refueling (stable at 1 speeds), measured at this time the generator voltage is about 16V, at this time the touch battery, found that the temperature is high, and there is a peculiar smell, so the initial judgment is that the generator regulator is damaged, leading to excessive electrical pressure of power generation. In order to further verify this fault, the engine B+ output end is broken off after the engine is started, and then the road test is carried out (at this time the battery meets the road test conditions), the fault no longer appears, and the acceleration is good. In the end, the generator was replaced and the fault was eliminated. Fault analysis: because the electric system is a more stable voltage, the engine speed is determined by different road conditions and load, and the generator is driven by the engine, so the speed of the generator is unstable and the voltage of the generator is unstable. In order to solve this problem, the generator set the voltage regulator. When the engine speed is rapidly increasing, the generator will increase the power generation capacity. In order to protect the whole electric system of the car, the regulator keeps the generating voltage within a constant range. When the regulator is damaged, the whole charging system can't get the adjusted voltage. At this time, ECU can't get the data. In order to protect the whole electrical system, ECU sends out instructions to control the engine speed and control the charging voltage.