Car alternator regulator

How to detect the alternator voltage regulator failure

The part diagnosis should be performed every 5,500-8,500 kilometers, or at the change of the season of the vehicle use. You can check the regulator serviceability by using a voltmeter. You should connect the instrument to the battery terminals and measure the voltage with the engine off: it should be approximately 12-12.8V. Then you need to start the engine: if the multimeter's readings range within 13,2-14V, the component is in good order. Then it is required to increase the rpm. The measured voltage should increase as well, but not over 14.8V.

The regulator removed from the car is examined in another way. You need a voltmeter, a 12 volt light bulb, a power module or a charger with current control, a few wires with terminals, and a battery. You should connect the battery to the charger, and the light bulb to the battery, connecting the bulb to the corresponding voltage regulator terminals using the wires. The voltmeter, if not integrated in the charger, is connected to the battery. After the power module or the charger is turned on, the light bulb should light up, and go out when you increase the voltage to 14.5V (on some vehicles to 14.8V). If, after reaching this threshold, the light does not go off, the voltage regulator needs replacement.

You may identify that the alternator relay voltage regulator needs diagnosis by the following symptoms:

• white bloom on the battery housing or on the car body in the area of ​​its location;
• hindered engine start;
• too high value of the charge current after 4-6 hours of continuous driving;
• light bulbs often burn out in the car lighting system.

Causes of the alternator voltage regulator failures

Transistor burnout is the most common voltage regulator failure. Typically, it is caused by either the interturn short circuit in the winding of the alternator stator or rotor, or the diode bridge improper operation. If the part fails too often, the alternator may need repair or even replacement. Often the regulator frequent burnout occurs due to its poor quality or non-compliance with the vehicle technical requirements, as well as with the installation of optional electrical equipment, for example, heated door handles.

The regulator contacts can be oxidized due to the moisture and dirt exposure, which prevents the signal passage through the electrical circuit. In some cases the problem can be solved by removing dirt and corrosion, as well as by more reliable fastening of the wires. In the regulators, combined with the brush assembly, the contact absence and, correspondingly, malfunction can result from the brushes wear.

The regulator correct operation can be impaired also due to the change of the clearance between the core and the armature, or slackening of the armature spring. And in some cases the part malfunction is caused by the voltage regulator improper adjustment.

Replacement of the alternator voltage regulator

The regulator replacement can be made both at a service station or by yourself. On many vehicles this will require removing the alternator. The procedure is as follows:

1. Disconnect the negative terminal from the battery.
2. Loosen the alternator upper fasteners, slightly move it aside and detach the drive belt from the pulley.
3. Completely unscrew the lower and upper bolts and dismantle the assembly.
4. Dismantle the alternator's back protective cover after releasing the clips.
5. Pull out the connector with the wires that connect the regulator and the diode bridge.
6. Unscrew the nut on the contact block bolt, and then unscrew the regulator fasteners.
7. Remove the failed part and install a new one in its place.

This procedure is generalized and may vary depending on the vehicle brand and model. You can find more detailed instructions in the car technical documents.