How to check a Bosch alternator regulator

Design of a voltage regulator and external signs of its malfunction

The use of a separate design is easily visually detected due to the fact that the relay is located in the gap of the current flowing between the alternator and the battery. In any form, the relay is a non-disassembled monoblock element, the body of which is filled with epoxy or other sealant. This means that the failed component cannot be repaired.

Failure of a voltage regulator is accompanied by undercharging or overcharging of the battery. Undercharging of the battery results in

  • the engine starts badly;
  • The starter is unable to turn the crankshaft;
  • In severe cases, the car is de-energized, and the remaining charge is not enough even to turn on the dashboard indicators.

Unpleasant consequence of battery overcharge is boiling of electrolyte. At the same time on his body in the area of the terminals and on the terminals themselves there is a white residue and leakage. External signs are not exhaustive, do not unambiguously indicate a faulty relay. Nevertheless, in case of their appearance a complex check of the generator circuits and circuit is performed, the list of procedures of which includes control of the serviceability of a voltage regulator.

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How to check the voltage regulator of a gasoline generator with a multimeter

The most common cause of failure of the automatic voltage regulator of a three-phase generator is a counter voltage or the wrong procedure for removing the load from the generator. most often, when a person at the end of work just turn off the engine of a gasoline generator or diesel power plant, instead of disconnecting the load of the consumer with the standard toggle switch. Also ATS often fails when connected makeshift welder or excessive reactive load.

Relay-regulator types

Exaggerating, there are only two kinds, but each works on the same principle, namely “cuts” or “increases” the voltage to the desired index.

How To Test an Alternator Part 3 Regulator and Brush Pack Replacement Slip Rings Test

Cases are not dismantled and tight and the other type (often filled with sealants or special adhesives), that is, they are not repairable. To be honest, they are cheap enough, especially at our VAZ, so it is easier to buy a new than to fiddle with the old.

These are the most common types, of course, used to be so-called combined with terminals, but they did not take root, because the device is not very convenient, so I will not talk about them.

If your relay “wrecked” is a constant overcharge, then it is worth changing it, but first you need to make sure that it is in it. Now there are only two ways to check: not removing on the car itself, and checking a relay that has already been removed. Let’s see both variants.

How to check the relay. regulator without removing from the car?

If your “regulator” is out of order. you will notice it very quickly, especially if it is winter and there is frost outside. The fact that there will be either “undercharge” or overcharge the battery. If the battery is undercharged you simply do not start your car. you come to a parking lot, you insert the key, and the car barely starts the engine, or does not start at all, sometimes even the lights go out.

If it is overcharged you will see the same problem, but it will be caused by boiling of electrolyte from ACB banks. You can indirectly determine by the rapid decrease of electrolyte in the battery jars and white film on the top of the battery, as well as on parts of the body under it. You should already think about and check the regulator relay.

But this is not our method, we need to make sure more accurately.

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For this we will use our voltmeter, we need to measure the voltage across the battery terminals, with the engine running. To begin with, I want to note that with the non-started engine normal voltage should be within 12.7V, maybe a little less, but if you already have 12V, then the battery needs to recharge! Or look for the reasons of undercharging.

  • Connect the probes to the terminals
  • If it is about 13,2 to 14 volt, it is normal.
  • increase rpm (say up to 2000 to 2500), voltage will start to rise, about 13,6 to 14,2V, this is also normal.
  • then try at maximum speed (over 3500), the voltage should be 14 to 14.5 volts, but no more!

If you have deviations, more or less, namely at any speed voltage remained at 12.7 volts, or even fell to 12 volts, it indicates a malfunction of the voltage regulator.

Also if the voltage is higher than 14.5 volts, for example. 15. 16 volts, once again the voltage regulator is faulty, you need to change.

To be completely honest, not always the fault indicates only not the relay, often the alternator itself fails. If the “regulator” is separately installed, you must first change it, if nothing has changed, remove the alternator and completely check the system. If the brush unit is combined with a relay, the alternator must be removed!

How to check a separate voltage regulator on an alternator

Separate voltage regulators may be installed separately from the alternator on older models of vehicles. Failure of such parts can also lead to overcharging or lack of charge of the battery, so you should check at the first suspicion of abnormal operation of this element.

Testing an alternator voltage regulator type 591 3702 01

The principle of checking a type 591 3702 01 voltage regulator is identical to other devices of this type. You must also connect the unit to a DC power supply and, by changing the output voltage on the power supply unit, set the moment when the indicator lamp turns off.

The peculiarity of the design of the regulator of the type 591 3702 01 is the output part which has contacts designated as “67” and “15”. Pin “67” is the “minus” of the system, so connect a suitable wire from the power supply which is connected in series with the bulb. Also connect the minus pin to the regulator’s “ground wire” (the metal fixture) Pin “15” is the positive side of the unit, so connect the positive wire to it.

Check the device according to the standard scheme. At first the operating voltage is applied, at which point the lamp should light up. When the maximum possible voltage is exceeded (14.5 V) the electric current in the circuit disappears.

The voltage regulator type 591 3702 01 can be checked more accurately on a special diagnostic test rig. Such an installation has an alternator, a battery and a voltmeter. The regulator is connected on the stand in the same way as when it is mounted on the car. After starting the test bench by regulating the alternator rotation voltage exceeds the cut-off threshold (14,5 V). Tripping of the device is registered by a voltmeter.

If a voltage regulator does not cut off the voltage supply when it reaches a critical level or there is no electric current immediately after starting the alternator, it is necessary to replace the voltage regulator, type 591 3702 01.

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How to test a three-level voltage regulator

Instead of a standard voltage regulator, cars may be equipped with a three-level voltage regulator. Such devices are more advanced and reliable. The difference between the three-level relays and the chocolates is that the cut-off voltage can be set at will by means of the integrated voltage regulator.

Three-level relays are tested according to the standard scheme, when an adjustable electric current source and a control lamp are connected to the relay. When performing the test, consider only the previously set cutoff voltage limits. That is, if with the help of manual adjustment has been set the moment of tripping at 14.7 V, then at this voltage disappearance of electric current will be normal.

Testing of alternator

If battery overcharge may be caused by a malfunction of a voltage regulator, then at an undercharge of the battery the part may be fully operational. Alternator malfunctions can cause a permanent or temporary lack of electrical current to fully recharge the battery. If the vehicle has a separate voltage regulator, this part can be easily excluded from the electrical circuit and thus verify the good condition of the alternator. The diagnostic operation is performed with the engine running as follows:

  • Disconnect wires from voltage regulator (pins 15 and 67).
  • Instead of a voltage regulator in the scheme should be connected to a 12 V incandescent lamp.
  • Disconnect the plus wire from the battery when the engine is running.

If the engine continues to run when the positive terminal is disconnected, the alternator of the vehicle is faulty. Otherwise, you should check this part and all additional elements involved in the transmission of electrical energy.

How to check a relay regulator

Failure of a voltage regulator is manifested by systematic undercharging or overcharging of the battery. The simplest check of the device is carried out with a voltmeter tester on a direct current within the range of 0 to 20 volts. When the engine is not running, connect the probe with the terminals of the battery and fix the reading of the voltmeter, which varies from 12 to 12.8 volts depending on the condition of the battery.

After the engine is started and look at the instrument readings: the voltage should rise to 13-13,8 V, depending on the crankshaft speed. Further increase of the revolutions should correspondingly increase the voltage. So, at medium speed it is 13,5-14,5 V and at maximum it reaches 14-14,5 V. No rise in voltage after starting the engine indicates a malfunction of the voltage regulator.

it is possible that the battery is not charged for another reason, for example, because of a defect in the alternator itself. In order to establish the diagnosis, the voltage regulator is removed for more accurate checking with a tester and a 12-volt lamp. In addition you need wires with terminals, power supply unit or charger in which you can regulate the current.

After connecting the relay to the circuit and turning on the power supply the lamp will light up. gradually increase the current with the voltage regulator and watch the voltmeter or the scale of the connected tester. The lamp should light up if the reading is under 14.5V and go out after exceeding 14.5V. If it goes back on after the reading falls below 14,5 then the voltage regulator is defective. If the operation deviates one way or the other, the relay will overcharge or not deliver the necessary current to charge, which is a reason to replace it.

Integrated relays, popularly called “chocolates”, used on older models of domestic machines, are tested in a similar way. The circuit is also connected to the power supply or charger through a light bulb, which should go out when the desired voltage limit is reached. Then you need to pay attention to the condition of the terminals, which may create additional resistance if they are dirty or oxidized and cause voltage loss if the relay is faultless.

Checking with a multimeter without disassembly

You can check the state of the relay with a multimeter. In this case there is no need to disassemble the generator. Before starting the diagnostics, it is enough to clean the battery terminals (their oxidation may affect the operation of the car and the readings of the meter).

  • First you need to start the engine and let it warm up for a few minutes.
  • Next, you need to connect the probe of the multimeter to the battery terminals. In this case, set the value of 20V on the device.
  • After that measure voltage. It must be within the range of 13.2-14В. This is considered a normal reading for most vehicles.
  • Now you need to increase the engine speed (up to 2-2.5 thousand). The voltage should increase by approximately 0.2В.
  • If it exceeds 3,500 RPM, the multimeter should show 14-14.5 V, but no more.

Serious deviations in the readings of the device indicate the presence of a broken voltage regulator.

Regulator malfunction or it is easier to replace than repair

The diagram shows the function of the generator operating state indicator with a voltage regulator. When the engine is not started, the current from the battery through the ignition key contacts comes to the generator, which provides its initial excitation. the lamp is on, it means there is no breakage in the circuit. After starting the engine, on the alternator terminals D and B appears voltage with almost equal value, the lamp goes out. If the indicator remains lit, it means that there is no proper excitation on the alternator, which indicates a break or failure of the unit itself.

How to check the voltage regulator

Do not repair the voltage regulator, but replace it with a new one. But before changing the voltage regulator you must be absolutely sure that it is the voltage regulator that is at fault.

Fig. Testing of voltage regulator from DC source

Checking is performed according to the scheme in which the terminals of the main rectifier B and an auxiliary rectifier are connected and connected to a direct current network with voltage up to 16 V. Connect the source minus to the regulator‘s minus pole. Connect pin D of the regulator to the plus side. Connect a test lamp between DF and B- leads. thus short-circuiting the regulator’s output transistor. Connect the alternator field winding between the same leads.

Fig. Voltage regulator trouble table

Checking the serviceability of the voltage regulator of an alternator

Inside each vehicle is a miniature power plant, a generator, which is responsible for generating power. If something breaks in it, the battery won’t work properly. The result is a suddenly stalled engine. For some reason it always happens at the most inopportune moment. To avoid being left without a car somewhere in the middle of nowhere, periodically check the alternator’s voltage regulator.

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