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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Wed Dec 16, 2020 5:57 pm 
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I fully agree with all that you said. Tell us more about that $50 oscilloscope.
Got my attention! One tool that I don't have in my arsenal but would love to have one.
They certainly have their place and usefulness when working on electrical issues on todays vehicles.

Nice article, but not fully correct for our 05 & 06 Jeeps. No surprises there! :lol:
It says Chrysler did not start using a "one wire" control until 2008, we know this is not true for our 05-06 applications.
None of the wiring schematics shown in the article (3 - 6) are correct for our Jeep diesels. May be true for some Gassers?

Has anyone tested for a PWM signal on the one wire on the voltage regulator at the alternator?
It would be very interesting to know what that signal looks like traveling through that single wire.

Quote:
Such a true statement: "it seems the Liberty CRD doesn't behave like typical Mopars in most ways" :banghead: :cry:


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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Wed Dec 16, 2020 6:41 pm 
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There are things like this:

https://www.amazon.com/dp/B009H4AYII

I use specifically this one:

https://www.picotech.com/oscilloscope/2 ... 0-overview

which is quite a bit more, but since I really don't know what I'm doing most of the time, I wanted to have good software and quality documentation to fall back on.. Pico often assumes the user is an idiot like me, and they have howtos on how to test a variety of common automotive sensors.

In the intervening years, things like this have started to appear:

https://www.amazon.com/dp/B08DG1C129/

and I've been tempted to try one. For what I need, high accuracy isn't *super* important - with automotive sensors you're generally looking for patterns so I think something like this would work great. And not having to drag my laptop into the garage would be a plus! But until the darn CRD stops bleeding me dry, I can't even think about it. :D

I would *think* most modern multimeters can measure duty cycle, so assuming my theory on operation is correct (and I'm *reasonably* sure it is) you should be able to throw a multimeter in % mode and read that wire. I don't know whether the control is + or -, but that would only take a moment to determine and swap the probes around. On some (most?) multimeters polarity won't even matter.

The gotcha is that without specs, I'd think it tough to correlate what you read with anything truly useful. The control module just says "gimme more" or "gimme less" based on its algorithm. Without knowing that algorithm, you'd never know if what you saw is correct or not for current conditions. Also, it'd be impossible to determine the functional max value ... like, is 50% duty cycle enough to get full performance from the alternator, or is 100% duty cycle required?

Just a WAG here, but probably the even though the dimensions are unique to the CRD, the alternator itself shares operational attributes with a bazillion other alternators. If the "family" is known, probably how it works is documented somewhere. That's true of Bosch, GM, and Ford... I'm sure it's true in Mopar-land too.

Here's the flavor...

https://www.youtube.com/watch?v=-zC24W7dEH8


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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Wed Dec 16, 2020 6:44 pm 
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This is more on the topic, using the same Picoscope I have... you can see the software at work, which is cool.

https://www.youtube.com/watch?v=7W5cB-di0zw

Man, this is why I love these guys...

https://www.youtube.com/watch?v=7HLY7sfctnk


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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Wed Dec 16, 2020 7:52 pm 
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Hopefully this video will settle the alternator/regulator debate:
https://youtu.be/8LPgLwTLilY

The alternator WILL self excite without any input from an external module.

When I replaced my voltage regulator I dissected the old one.
Inside I found an integrated circuit and two capacitors.
It was the capacitors that caught my attention.

I’m not an electrical engineer nor an automotive engineer but here is my theory of operation:
As long as those capacitors have a charge, the alternator will excite and charge all in its own. However, if left unused for a long period of time the capacitors can drain and will need an external input to get it charging again.
This is definitely true with a NEW regulator that I verified. But I only verified at idle and didn’t verify exactly where that one small wire gets it’s voltage from.

It’s also possible that the alternator will self excite at a certain rpm above idle, just like the good ol GM 1-wire alternator.
But I couldn’t verify that.

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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Wed Dec 16, 2020 9:24 pm 
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I think this is typical operation - without any intervention from the control module, the alternator goes to full charge. The caution here could be what that Remy article suggests - that charging voltage may go very high as rpm.increases in this situation. Or, it could behave like a GM alternator and simply run at 14v. That's how the alternator in my Fiero is wired... The computer control is simply not plugged in. It self excites, I get 14v.

I think the only point of this tangent was to demonstrate that jagster's low speed voltage fluctuation could be the result of the control module getting bad information and/or poorly controlling the alternator. If we knew the answer to the "uncontrolled voltage" question, we could advise disconnecting the control wire and seeing if the problem goes away.

I don't think it will... I think the issue is either the VR or the alternator itself... But wtf do I know?


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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Wed Dec 16, 2020 11:14 pm 
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What a great discussion by all and sharing of information on the alternator charging and operation subject.
Unfortunately as usual it always seems that the more we know and question on these unique vehicles, the less we fully understand at the end of the day and end up with more questions than answers. :banghead: :banghead:
As to jagster's issue, some diagnosing with a good voltmeter may tell him where the root cause of his problem lies.....
I think several of us are very curious. Wish he was close by, I would gladly help him figure out his issue.
:POPCORN:

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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Thu Dec 17, 2020 2:51 pm 
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It's really pretty baffling how poorly the documentation on these trucks is assembled. Since I don't have much experience I have to rely on a lot on the FSMs, and it's very annoying to have to compare '05 and '06 manuals to see which has better information, or the information at all! So many times details are just summarily left out. Same with the parts catalogs. You can't even rely on generic VM documentation because so much was customized for the Jeep application. If it wasn't such a unique and fun truck I would be very upset with my choice to buy one! :D


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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Thu Dec 17, 2020 5:47 pm 
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thesameguy wrote:
It's really pretty baffling how poorly the documentation on these trucks is assembled. Since I don't have much experience I have to rely on a lot on the FSMs, and it's very annoying to have to compare '05 and '06 manuals to see which has better information, or the information at all! So many times details are just summarily left out. Same with the parts catalogs. You can't even rely on generic VM documentation because so much was customized for the Jeep application. If it wasn't such a unique and fun truck I would be very upset with my choice to buy one! :D

Agree, the lack of information or correct information on some areas of the CRD in the FSM's and Parts Lists can be so totally frustrating to say the least! :furious: :banghead: :5SHOTS:

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05 Jeep Liberty CRD Limited :JEEPIN:
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount

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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Tue Dec 22, 2020 3:34 am 
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Agreed that the KJ documentation is so bad and very conflicting.

They obviously have "cut and pasted" sections from the early KJs to the 2005/6 models! :?

An example is that the 2005/6 Documentation still insists that there is a "Battery Temperature Sensor under the Battery"....not true for the newer KJs! :(

I like WWdiesel's picture of the rear of the alternator showing the Voltage Regulator...definitely worth replacing that module for weird charging problems! :wink:

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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Mon Apr 19, 2021 6:13 pm 
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Second test drive today after tightening ground nut on stud next to JB/BCM. First 15 miles Liberty performed well. Ate lunch then went to O’reillys Auto Parts across street to get 2 1/2” exhaust pipe to replace catalytic converter. Left wife in Liberty in park with ac on, engine running and she reported intermittent engine bump. I felt/heard it also so turned off ac and it went away. Stopped to get diesel and left engine running. When I got back after paying for fuel the instrument panel was lit up including battery and flash/accelerator. Drove a couple of miles than pulled over to turn off and restart engine to clear instrument panel. Liberty wouldn’t start. Battery voltage was 11.9. After jump start voltage at battery was 11.9 to 13.7 for a few seconds than 11.9 to 13.7 again. Drove home with no icons on dash and parked in shop. Disconnected and charged 1 year old battery. Liberty has 153k miles and never had a charging issue since I got it with 90k miles. Going to start engine and check voltages at alternator and battery. Going to check positive connections. Been checking grounds and added a few for insurance.

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 Post subject: Re: The Dreaded Alternator Pulley
PostPosted: Tue Apr 20, 2021 10:59 pm 
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2005 Liberty with electrical issues. Took old alternator to O’Reillys and it tested ok. Gave me the heebee geebees because I then figured the forward control module was bad. Bought and installed new alternator and cleaned forward control module plug and socket. Installed ground from fcm case to battery negative. Test drive revealed all electrical gremlins are gone. In hindsight should have been checking battery and alternator output voltage at first sign of trouble. Had been doing this previously and it was always good so let that slide at first sign of trouble. Can’t relax dealing with electrons on this thing.

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2005 Silver Liberty CRD
Provent, 3.7 intake, K+N filter
ARP studs, Hemi pu tcm
In tank harness/fuel pump
Airtex rear bag, Fujimoto valve
Upgraded lifters, exhaust valves, fuel head
Florida torque converter, ID trans pump
Transgo shift kit, GM fan
2 micron filter, Bilstein shocks
Viscous heater delete


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