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2005 Chrysler Town and Country 3.8 alternator and battery draining issues

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08 Oct 2019 18:27 #34085 by MOROSO321
Having issues with my alternator not reaching above 13.7 V. I watched your video Paul. The one that you were testing the alternator that was computer controlled. My alternator is not reaching 14 volts, it’s only reaching 13.7 V. The circuit is power side switched. Brown/grey wire is my control wire. Black wire is the ground. I perform the power to power voltage drop test and it read 0.030. And the ground read 0.020. This alternator already killed my battery what should I do Paul why am I not doing right?
By the way I noticed that when I did a key on engine running test on the control wire the voltage was 2.62 and it was fluctuating according to the wiring diagram am I not supposed to be reading 12 V. Little help buddy thank you.

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08 Oct 2019 18:29 #34086 by MOROSO321
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08 Oct 2019 18:30 #34087 by MOROSO321
That was the reading on the control wire plugged in, koer backprobbed.

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08 Oct 2019 20:48 #34090 by Monde
For you to get 13.7 v, you have to have control from the pcm. If you get 13.7 v, your alternator is charging.Are you losing the voltage to the point the car dies?

Vouloir, c'est pouvoir.

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09 Oct 2019 05:03 #34094 by MOROSO321
No Monde. The minivan is not shutting down.
So why would I be getting this reading?

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09 Oct 2019 06:39 - 09 Oct 2019 07:06 #34097 by BrandonF
What do you mean "not shutting down"....Or are you refering to a parasitic draw (a key off draw). You may need to make sure she is under the general 50mA draw. Most I typically get a hold of however, are much lower. If we are understanding your situation correctly.....No crank, dead battery. Also, the only computer controlled alternators I have ever had to test, have had to be done with a lab scope. This can possibly be considered a "monitor" and "command" signal so to speak...... maybe, heck i don't know lol. But It can be interpreted on a lab scope with the monitor signal generally being a constant square wave form and the command evenly pulsed with another square waveform. That may not make sense so i'll include a picture (off of my verus because I cant email the dang picture to myself from the verus) that is actually an IGT/IGF signal from a toyota pickup's ignition system that has a very similiar waveform. But I sounds like you'll need to go the first route.....good luck my friend.
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09 Oct 2019 07:15 #34100 by MOROSO321
Sorry, I mean that the car is not wanting to turn off.

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09 Oct 2019 07:18 #34101 by MOROSO321
No Brandon, the van starts, I was under the impression that I needed to see 14v plus on my meter to tell me that my alternator is charging my battery. That’s all. I wasn’t aware that the threshold was 13.5 to 15.0v.

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09 Oct 2019 07:23 #34102 by MOROSO321

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09 Oct 2019 07:33 #34104 by MOROSO321
By the way, what would my lab scope settings be if I wanted to see the alternators waveform? I have an old modis, not updated at all. thanks.

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09 Oct 2019 11:01 #34115 by BrandonF
These signals can vary per manufacturer but they are generally large enough that you can start on a 20v scale and 500ms or 1s time base and then work down from there for detail and repetition, as Mr. Paul has taught us. I'm still possibly not understanding your issue though. So, When you are turning the key off, the vehicle is still running? If so, you may need to start at the electrical side of the ignition switch.

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09 Oct 2019 11:25 #34116 by MOROSO321
No Brandon that’s not it buddy. The issue is that I’m trying to make sure that my alternator is charging my battery properly. And I thought that if I didn’t see 14 volts, my alternator was bad. Which is not the case. The alternator is putting out 13.7 volts, even with all my accessories on.

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09 Oct 2019 12:48 #34118 by BrandonF
Oh, my bad brother. Got totally confused when you said the car wasn't wanting to turn off. I hope you get her handled bud.

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