The mileage is about 146 thousand km, the Santana 2000GSi car equipped with AJR engine and manual transmission. During the driving process, the charging indicator light does not go out. Fault diagnosis: after the test, it is found that when the vehicle runs normally and the engine and generator speed is above the medium speed, the charging indicator has always been in a constant light state. The possible causes are analyzed as follows: generator failure, regulator failure, and line contact resistance. First check the tightness of the drive belt between the engine crankshaft end pulley and the generator pulley, press the fan drive belt with the hand thumb, the deflection of the drive belt is 4mm, the tightness is normal, and there is no loose or slippery phenomenon. Then the engine is flameout, the ignition switch is hit to the ignition gear and the 20V DC voltage shift is hit with the multimeter. The voltage value between the "15" terminal and the iron lap of the ignition switch is checked. The voltmeter is shown to be 12V, indicating that there is no problem between the ignition switch and the battery and the power connection line. Next, disconnect the connector T between the central circuit board and the generator D + terminal. The blue wire leading to one end of the generator is grounded, the charging indicator is still not extinguished, indicating that the central circuit board is in normal circuit, and the fault may be in the generator or the electronic regulator. The rear end cover of the generator is removed and the "F" connection column of the electronic regulator is reloaded after the "-" connection post is reloaded into the generator. The engine is restarted and the speed is gradually increased to the medium speed. At this time the charging indicator is extinguished, thus indicating that the fault is located in the electronic regulator. Troubleshooting: after changing the electronic regulator, test run and troubleshooting.