Connect the DIS tester and select the test modes — "Measurement system" and "Generator test". If the battery charge indicator is constantly on, then you need to:
- remove the voltage regulator and check the amount of protrusion of the carbon brushes, replace them if necessary. The minimum length of carbon brushes "A" is 5.0 mm (A. Fig. 353), if less, replace the generator voltage regulator.
If the battery charge indicator goes out when the engine is running, then it is necessary to check the value of the regulated voltage; if it is not achieved, then it is necessary to replace the regulator.
The generator with BSD and the voltage regulator should be tested using a comparative analysis of oscillograms, for which purpose connect a DIS tester and set the measurement modes:
- function selection;
- the car as a whole;
- engine and transmission;
- voltage and current regulation;
- power generation;
Process the results of test blocks and oscillograms.
The oscillogram of a working generator is shown in Fig. 3.54.
Oscillograms of a faulty generator:
- break of one phase (fig. 3.55,a);
- interturn short circuit (fig. 3.55, b);
- open circuit in negative diode (fig. 3.55, in);
- Short circuit in positive diode (fig. 3.55, g);
- open circuit in positive diode (fig. 3.55, d);
- open circuit in the diode and/or excitation winding (fig. 3.55, e).
In all these cases, the generator needs to be repaired or replaced.