How to Test Voltage Regulators

Hi,

How can I test the voltage regulator without replacing it with a new one?
The pencils seem to be fine.

Thank you.

http://www.cheesebuerger.de/smilies/verbluefft/14.gif

How about measuring the initial voltage?
Engine off: ~12.6V
Engine on: ~13.8V

If the voltage doesn't increase significantly when the engine is running (compared to when it's off), or if the voltage exceeds 14.5V, then your voltage regulator is likely faulty (assuming the alternator is working correctly).

Regards,
Private.

Are there not also voltage regulator circuits that operate at 14.4 volts?

And then, the measurement error is no longer so significant when it comes to the 14.5 V limit.

Don't switch to ckone at 14.45 unnecessarily (if the 14.4 version even exists).

m;

dieselmartin wrote:

Aren't there also regulating regulators for 14.4 volts?

AFAIK, yes.

Then, the LiMa terminal might also have 14.4V, but due to cable and internal resistance, the battery receives a few tenths of a volt less (depending on the current load).

Checking the exposed regulator is also an option.
Connect a light bulb to the carbon electrodes (the cold resistance should not be significantly lower than the resistance of the alternator winding), and connect the voltage of a suitably powerful, adjustable power supply to the regulator ground and the exciter input.

Slowly increase the voltage towards 14 volts.
The bulb must glow normally and switch off abruptly when the rated voltage is exceeded.
By slightly adjusting the control setting up and down around a "critical" control point, the light bulb can be turned on and off.

A regulator can't do more than that.

If, instead of a clear switching point, a faint flickering can be observed, then the controller is malfunctioning.

In the Audi, it's channel 20 in the climate control system. You can read the voltage there.

Best regards,
Uwe

So, I finally got around to measuring it.

Engine off: 12.6V
Engine on: 12.2V

I really hope the Lima isn't broken.
Are the voltage regulators the same in all newer VW models? I have a Golf 4 available that I could borrow the voltage regulator from to test.

Best regards,

ckone wrote:

Engine off: 12.6V Engine on: 12.2V

Hi,

This suggests that the charging system is no longer working at all.

This can be caused by worn-out brushes (besides the regulator), or the pre-excitation may not be sufficient -> does the charger indicator at least light up when the engine is not running?

A broken cable between the alternator (LiMa) and the battery is also a possibility.

Hi,

Hold on... did you measure immediately after starting, or only after the afterglow finished (up to 4 minutes later)? The afterglow consumes a significant amount of power and, at least in my case, causes a drop of approximately 0.8 volts in the on-board voltage at the measurement point (cigarette lighter socket, which is powered by the interior power supply).

Normally, I get around 14.2 to 14.4 volts while driving, and about 12.6 volts with the engine off.

Even during the preheating phase at -15 degrees Celsius, the voltage can drop to 11.6...11.8 volts.

Best regards,

Jan.

... does the charger light at least come on when the engine is not running?


It doesn't burn, I just noticed that for the first time. I never pay attention to that usually.

Where could the error be?

ckone wrote:

ulf wrote: ... does the charger indicator at least light up when the engine is off? It doesn't burn, I just noticed that for the first time. I never pay attention to that usually. Where could the error be?

(I meant, of course, chargecontrol)
-> in the simplest case, due to a burnt-out bulb (depending on the vehicle and year of manufacture).

Otherwise:
Cable breaks between the instrument cluster (KI) and the alternator (LiMa), a detached/corroded connector on the alternator, worn-out carbon brushes, a faulty regulator, an interruption in the alternator rotor winding, the instrument cluster is not receiving any voltage (are the other instruments working?), and for those who are very detail-oriented, there might be other possibilities .

Okay, so all my other instruments are working fine, and the carbon brushes are also in good condition. The connector at the alternator is neither loose nor corroded.

I will measure the DF line to the engine control unit tomorrow and check the wiring between the alternator and the instrument cluster.

That has nothing to do with the DF line. The lamp or LED is connected to D+.
To test it, you can simply connect a 1.2 or 2W light bulb between +12V and D+. If the light doesn't turn on, the regulator or the rotor (unlikely) is broken. An even simpler solution is to buy a new regulator and install it. If it wasn't the problem, you'll have a spare for later.

greetings
dieter

I don't have a D+ connection that's directly linked to the AI.
I have an L-wire that connects to the control unit for the vehicle's electrical system.

Quote:

I do not have a D+ line that connects directly to the AI. I have an L-wire that goes to the control unit for the vehicle's electrical system.

Ugh, that modern-day nonsense .

Does the Lima already have a processor inside?
Okay, then I'll retract everything I said and stay out of it. Fortunately, I only have the MSTG and nothing else like that.

I found the error; the cable from the regulator to the control unit for the vehicle's electrical system was torn off at the connector located below the starter .
I fixed it, and now it's working properly again.

Thank you for your help .