You need to check the generator if you notice the following symptoms: when the engine is running, the battery discharge indicator lamp flashes or is continuously on; the battery is discharged or overcharged; the headlights are dim or the brightness of the light changes as speed increases; you hear a rattling or quiet sound when the engine is running. The diagnostics includes a visual inspection, checking the degree of tension of the generator belt, the condition of the bearings and the battery voltage at rest and with the engine running. In addition, the brushes and rings of the generator, diode bridge, voltage regulator, stator and rotor are checked.