Check the alternator with the test light: In the diagnosis of alternator failure, in addition to measuring with the instrument, you can also use the test method to check. When it is determined that there is no charge failure, you can not start the engine, turn on the ignition switch, the end of the test light pin and the generator magnetic field terminal phase, and the other end of the stylus touch the generator shell, Light, indicating that the battery to the generator magnetic field terminal. At this time you can remove the generator armature terminal wire, start the engine, the test light one end contact pin contact armature terminal; the other end of the generator shell, and make the engine slightly higher than the idle test (not allowed to high ), If the test light does not shine (see Figure 50), or the light is weak, for the generator inside the fault.

First, the appearance of inspection: a closer look at the generators, regulators, ignition switch whether the loose line, the generator is firmly fixed, V-belt is loose or oil slippery.

Second, check the regulator: the two lines connected together (that is, the ignition switch to the regulator, the regulator to the generator magnetic field wiring line), start the vehicle if the power generation, then the failure in the regulator (platinum contact ablation, Contact spring tension is weak or resistance blown, etc.).

Third, check the generator: Remove the generator magnetic field terminal wire, open the ignition switch, the removal of the thread in the magnetic field terminal touch, if blue and white spark, said the magnetic field circuit is good. If no spark indicates that the carbon brush is not in contact or the field coil is broken.

Fourth, with a screwdriver in the generator back (201 bearing cover), check whether the magnetic suction. The normal generator should have a clear suction, if no suction or suction is weak, then the excitation circuit is faulty.

Fifth, the bearing loose, cover deformation, armature shaft bending, will cause the collision "sweep chamber", so that the coil ablation, the generator can not work properly.