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2003 Dodge Grand Caravan tested at Autozone as bad alternator but NOOOO. Need help then

2003 Dodge Grand Caravan 3.3L. Autozone tested my battery and said it was bad, probably due to a bad alternator. So I replaced the battery, they tested my system and said the alternator regulator was bad. I buy a new alternator and replace the old one. I go back to autozone and have them test my system with the NEW alternator and they tell me the regulator is bad. So I had them test my OLD alternator in their in-store alternator test thing… it says there is nothing wrong wit the old one. So I am going toswap the old one back into the car and get my money back on the new one they wasted my time with. Now for the question. Why is the test system telling me my regulator is bad and what else can I check and how?

The voltage regulator isn’t part of the alternator. Your vehicle has EVR or Electronic Voltage Regulation which is controlled by the Powertrain Control Module or the computer. If the charging system tests for no voltage regulation the PCM is replaced.


Checking for proper connection between the PCM and the alternator should also be done before replacing the PCM.

OK, so this Electronic Voltage Regulator or Powertrain Control Module… is this the part name I can look up in order to purchase and replace it? I am only finding accessory parts for installing a second battery when I search for these. BTW-thank you for an answer, I just don’t know enough to make use of it yet.

The voltage regulator circuit is inside the PCM module so if the circuit is faulty you would need a new PCM. You still should make sure the trouble isn’t with the wiring between the alternator and the PCM before you purchase another one.

ok. do i check the wiring visually, with a voltmeter, or pay someone to check it? I am a novice at best.

I would question the accuracy of thier diagnosis. Battery failures are common, they wear out. Charging system failures are not so common. I have seen many vehicles come in from these types of places for charging system repairs (warranty) and there was nothing wrong with the vehicle, the battery was already replaced.
Check the battery voltage with the engine running, 13.0- 14.5 volts. Charging system voltage varies depending on battery tepurature.

If you have a voltmeter and know how to use it you can verify the voltage is the same at both ends or check the continuity at both ends of the wire.

OK I have questions , took caravan to O’Reilly’s guy said that we have a bad diode in our alternator putting out a alternating current causing our battery to go bad, or could it be in the voltage regulator? is this correct?

Also our charging system says we are getting voltage

You can still have voltage output with a bad diode inside the alternator. A shorted diode will cause AC to get to the battery. Not good. You should have less than 0.1 volts of AC ripple voltage across the battery while the engine is running around 1,500 RPM.

First this is no job for a novice, second what symptoms are you having with the vehicle ? What problem are you trying to solve? A failing starter motor will make you think you have a low battery as it needs much more juice to operate the starter for instance. I dont know what issue we are actually trying to prove out here besides the competence of some guy at Auto Zone… which I could write a dissertation on in and of itself…