How to check the generator?

How to check the generator?

If you look at that and understand how to check the generator on a vehicle operation is necessary to have little knowledge and some tools.Usually this test is performed before the repair of the unit, to find out what is the cause of the problem, and has previously counted on, in what expenses it will cost you.

himself will not deceive, and after decide to check the vehicle generator work, will know exactly what needs to be replaced or repaired.To check the generator car is necessary to get an ohmmeter with a large measure of resistance.

Four main stages check:

  • check the integrity of the generator stator winding;
  • checks of the voltage regulator;
  • testing of the generator capacitors;
  • check generator diode bridge integrity;
  • check bearings.

stator integrity check generator

To check the stator windings use ohmmeter.Measure the resistance of the field winding.The results will be in the range 4-11 ohms.If the results are different - there is a break in the winding.

Then check the insulation resistance of the generator.One of the probes of an ohmmeter is connected to one of the contact rings of the stator and the other putting a probe in the stator housing.The result of the measurement should be infinite resistance.If not - winding earthed.

Check serviceability of the voltage regulator in the alternator

first step is to inspect the brushes.Their projection of holders should not exceed 5 mm.The brush should walk freely in the holders must be intact and not worn out.Then connect the positive terminal to the output device, and the weight of the negative voltage regulator.We connect a control bulb to the brushes.Serve

13.3 volts at the regulator, and the lamp should light up.After increasing the voltage to 14.3 volts, the control lamp goes out because the regulator has ceased to give the voltage on the brush.When the voltage drops to 13.3 volts, the lamp should work.


performance capacitors Connect the ohmmeter to the condenser.If it is OK, then regardless of the polarity, the initial resistance increases smoothly and soon ceases to change.This is an indication of health of the capacitor.

You probably realize that check the vehicle generator is not difficult.Required to have some training, dexterity and set the instruments, which can be purchased at any automotive market.

Checking alternator diode bridge integrity

To test a diode bridge vehicle generator, set the ohm meter to check the position of the diodes.Connect the positive terminal ohmmeter to ground diodes."Minus" terminal connected to the output of the diode.If the resistance is infinite - diode is good, but if the device provides other parameters, the diode needs to be replaced.

next step - replacing the provisions of the ohmmeter terminals reversed.resistance results should be near zero.So we check each diode to produce an accurate result.

Next check whether the diode on the body punches.The positive terminal ohmmeter touch plate on which there are diodes and the negative terminal, as in the previous embodiment, to the output diode.At zero resistance - the diode is faulty, and an infinite - OK.


bearing considered here only the electric component of the generator fault, but we must not forget also about mechanical problems with this type of device.It should not forget about the most common problem in generators, is the failure of the bearing device.

Check vehicle alternator bearings at its performance is not so difficult.Typically, this generator produces no pleasant rasping noises that could be heard distinctly, when you are near the machine or in the cabin.This problem occurs in older generators, and the new, modern devices.

Here, basically, a lot depends on the right and adjust the tension of the drive belt of the generator.In the case where the belt will draw, then soon you can get ready for a serious overhaul of the generator bearings, as a rule, this leads to the discharge of the battery and the upcoming release of its failure, especially in winter.

The first signs of this problem, it is flashing control light battery, which is located on the vehicle instrument panel and has a red color.If this indicator you are not available, which is quite rare in today's cars, get the special display unit with a set of LEDs, which is mounted in the cigarette lighter connector and indicates the battery's charge.

There are more "advanced" electronic counterparts, but functionally they are quite different and are much more expensive.