You should see approximately 13.5 to 14 VDC. If you are seeing 12.0 to 12.6 then either the regulator or the alternator is shot. Switch the volt meter to AC and repeat to see if any alternating current is getting through the DC regulator, if so then the regulator is shot.
Full Answer
What are the symptoms of a failing voltage regulator?
Bad Voltage Regulator SymptomsToo High Voltage in the Battery.Dead Battery.Battery Light or Check Engine Light.Inconsistent Operation of Electrical Components.Vehicle Dies While Running.Dimming/Pulsing Lights.
How do you test a VW voltage regulator?
2:326:23Vw voltage regulator charging system generator - YouTubeYouTubeStart of suggested clipEnd of suggested clipGround your your D F okay and then check power to your to your to your D plus. It should go up toMoreGround your your D F okay and then check power to your to your to your D plus. It should go up to like 35 volts.
How do I know if my voltage regulator is working?
0:232:18How to Test a Car Voltage Regulator - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd what you do is you put your multimeter clamps directly on the battery. Terminals. Positive redMoreAnd what you do is you put your multimeter clamps directly on the battery. Terminals. Positive red to positive and black to negative. And you set it to voltage.
Does my car have a voltage regulator?
The voltage regulator is usually found inside or on the back of the alternator case. Increasingly, though, late-model vehicle have the engine control module (ECM) regulating alternator voltage output through a special circuit.
Do you need a voltage regulator with an alternator?
Without the alternator voltage regulator, the input voltage would be too great and overload the electrical systems in your vehicle. To prevent that, the voltage regulator functions much like a linear regulator in that it ensures the alternator output maintains a steady charging voltage of between 13.5V and 14.5V.
Can you bench test a voltage regulator?
1:346:27Bench testing a voltage regulator - YouTubeYouTubeStart of suggested clipEnd of suggested clipBelow 14.8 it's charging when it goes above 14.8. It stops charging. So what that means is you canMoreBelow 14.8 it's charging when it goes above 14.8. It stops charging. So what that means is you can actually test your voltage regulator either on the bench or even in the car with a test light.
What causes a voltage regulator to fail?
It might be due to a host of other causes, including forgetting to switch off your lights, a problem with the alternator, or simply an old battery that needs to be replaced. But it could also be because of poorly managed current due to a bad voltage regulator.
How do you test a regulator?
With your car still in park, slowly press on the gas until your car reaches 1,500-2,000 RPMs. Read the output on the multimeter. The regulator should cap the output of your battery at around 14.5. If the voltage reads over 14.5, it probably means that you have a faulty regulator.
How do I know if my alternator voltage regulator is bad?
Probably, the most common symptom associated with a bad regulator is flickering, dimming, or pulsing lights. To be more specific, you may notice that the vehicle's: Headlights fluctuate between bright and dim, without you doing anything. High beam isn't working as expected.
Can you replace voltage regulator on alternator?
If it registers battery voltage only, the fault is in the alternator or its wiring, or in a field isolating relay if fitted. If it registers an excessive charge (15 volts or more) the regulator is faulty and you should replace it.
The alternator charges the battery and provides your car with a constant source of electricity while the engine is running
The voltage regulator does just what it says: it regulates the voltage from the alternator. Your battery should read a little more than 12 volts with the engine off. Next check the voltage of your charging system under load, the voltage should be within 13.2: 14.5 volts d/c.
Project Photos
Figure 1 Turn your alternator pulley side down on your bench. The voltage regulator is partially obscured by a plastic cover on the back of the alternator. Remove the two nuts (one 13mm (blue arrow) and one 15mm Yellow arrow)) and the one Philips head screw (red arrow) on the back and then lift the plastic cover off.
