LOST JEEPS
http://www.lostjeeps.com/forum/phpBB3/

Bad alternator?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=80731		 Page 1 of 1
Author:  irunmiles [ Mon Nov 24, 2014 7:25 pm ]
Post subject:  Bad alternator?
Tonight I noticed that my dash lights seemed dim, and soon after my headlights dimmed. Then the lightning bolt warning light for the electronic throttle control (ETC) came on, followed by the battery light and ABS light. I made it into my garage and turned the engine off. I tried to restart and got nothing.

I'm guessing that its a bad alternator. I replaced the alternator in Dec 2011 with an Auto Zone lifetime. So should I yank the alternator and have it tested?

I've also been going through batteries every ~18 months. Could this be due to the alternator also?
Author:  Rocky05 [ Tue Nov 25, 2014 5:17 am ]
Post subject:  Re: Bad alternator?
Could be your alternator. Try charging the battery and if it starts, test the voltage across the battery terminals while the engine is running. Voltage should read 13.5 to 14.2 with working alternator.
Author:  Drewd [ Fri Nov 28, 2014 12:32 am ]
Post subject:  Re: Bad alternator?
Probably your alternator decoupler. The alternator on our vehicle is very reliable. I have 140,000 trouble free miles on mine and replaced the decoupler several years ago.

I
Author:  papaindigo [ Fri Nov 28, 2014 10:26 am ]
Post subject:  Re: Bad alternator?
Most likely issue is alternator and/or alternator decoupler pulley. Check the latter at idle by looking down (may need grab a flashlight and remove plastic engine cover) the serp belt at the serp belt tensioner; if it's barely twitching decoupler is ok but if it's bouncing decoupler is bad and will eventually destroy tensioner. Otherwise have a good auto electric shop (best not start at Auto Zone as they have an incentive to "not" find a problem with their alternator) check alternator output which can be done on the vehicle.

Assuming you are buying "good" batteries (e.g. 800+CCA and a warranty period of 4+yrs) you should not be replacing them every 18 months. If you are getting 2yr warranty batteries then every 18 months is not unreasonable.
Author:  Rocky05 [ Sun Nov 30, 2014 9:33 am ]
Post subject:  Re: Bad alternator?
papaindigo wrote:
Most likely issue is alternator and/or alternator decoupler pulley. Check the latter at idle by looking down (may need grab a flashlight and remove plastic engine cover) the serp belt at the serp belt tensioner; if it's barely twitching decoupler is ok but if it's bouncing decoupler is bad and will eventually destroy tensioner. Otherwise have a good auto electric shop (best not start at Auto Zone as they have an incentive to "not" find a problem with their alternator) check alternator output which can be done on the vehicle.

Assuming you are buying "good" batteries (e.g. 800+CCA and a warranty period of 4+yrs) you should not be replacing them every 18 months. If you are getting 2yr warranty batteries then every 18 months is not unreasonable.



/side note. Has anyone ever experienced an alternator coupler fail in the open/ not charging position? Inquiring minds would like to know....
Author:  thermorex [ Mon Dec 01, 2014 1:49 am ]
Post subject:  Bad alternator?
Rocky05 wrote:
papaindigo wrote:
Most likely issue is alternator and/or alternator decoupler pulley. Check the latter at idle by looking down (may need grab a flashlight and remove plastic engine cover) the serp belt at the serp belt tensioner; if it's barely twitching decoupler is ok but if it's bouncing decoupler is bad and will eventually destroy tensioner. Otherwise have a good auto electric shop (best not start at Auto Zone as they have an incentive to "not" find a problem with their alternator) check alternator output which can be done on the vehicle.

Assuming you are buying "good" batteries (e.g. 800+CCA and a warranty period of 4+yrs) you should not be replacing them every 18 months. If you are getting 2yr warranty batteries then every 18 months is not unreasonable.



/side note. Has anyone ever experienced an alternator coupler fail in the open/ not charging position? Inquiring minds would like to know....


The decoupler name is a bit misleading. What happens is that the computer cuts the plus (the "energizer" wire for the alternator - the only thin wire that plugs on the top of the alternator - diesels have only one wire, gasolines have usually 2, the other one goes to the ignition coil) when charging is not needed, so alternator just spins without producing any electricity. When computer "senses" that charging is required, it powers back the energizer wire, which just creates a magnetic field in the alternator so the rotation of the rotor will produce electricity which will start charging the battery. When this happens, there will be a sudden mechanical resistance caused by turning the alternator rotor in an electromagnetic field -generated with the current from the energizer wire (which is not present when the energizer wire is not powered up), this is where the decoupler (which is purely mechanical - a spring and/or some clutches that is supposed to make that "shock" smoother) comes in place. So the decoupler, at least in theory, can't fail in "no charge" position since the decoupler does not turn on/off the charging, the energizer wire does that. Older charging systems had earth magnets which didn't need any energizer, they were always on, and turning the rotor in the stator that had earth, permanent magnets always produced electricity, you can't turn that off unless you stop turning the rotor.

As a side note, I am not sure how exactly the decoupler in the Crd is made, I think it's a combination of clutches (thus the red dust when the coupler goes bad) and some springs, but when it fails you won't miss it, sounds so bad that you'll definitely notice.

Oh, btw, don't mean to patronize you, just thought that a bit of detail won't hurt.


Sent from my iPhone using Tapatalk
Author:  Billwill [ Mon Dec 01, 2014 4:10 am ]
Post subject:  Re: Bad alternator?
I slightly disagree with thermorex here on some of his suppositions.

Firstly the alternator will always be charging....not switching on/off as required. As soon as the engine starts running electricity will be used up....to power the PCM/ECM/BCM etc, fire the injectors and run the blowers.
The PCM on a gasser senses the battery voltage somewhere...near to the ignition switch I believe and ups the current going through the alternator field coil to bring the voltage up to a reasonable value. The gasser alternator....and early Export CRDs...do not have a voltage regulator built into it so this is how the voltage is regulated....hence the two thin wires going to the alternator for the field coil.

The 2005/2006 CRDs have the regulator built into it now and I believe that Keith stated that a single "wakeup" wire is used to get the regulator working after a few seconds of running or once you get up to 2,000 RPM. This means that engine is able to turn over easier without the drain of a charging alternator.....yes you may get some shock to the system as the alternator kicks in which the de-coupler clutch will handle....the Theory of Operations in the manuals state that there is little shock to the alternator clutch from any sudden electrical demand.

The reason for the mechanical clutch de-coupler for all CRDs is that the 4 cylinder diesel has such an uneven power stroke that the serpentine belt would effectively speedup/slow down with every power stroke which is not good for the components running off of the belt. The de-coupler clutch is effectively a one-way clutch that lets the serpentine belt carry on moving at a constant speed in one direction without any slowing down/speeding up. If this clutch seizes up you get the bucking up and down of the serpentine belt with early failure of the belt or tensioner pulleys. If the clutch had to stop engaging completely then the engine would run off of the battery until the battery goes flat but I have never heard of this happening.

The six cylinder 3.7 gasser has a smoother power stroke so does not need this de-coupler clutch.... the 2.4 gasser 4 cylinder has a clutch on its alternator similar to the CRD.

The circuit diagrams for the 2006 as available in the Service Manuals actually do not show that the CRD alternator works in this manner....they show it working exactly as the gasser 3.7 works ie. the voltage regulator sits inside the ECM exactly as the 3.7 gasser has it in its PCM......there are plenty of mistakes in the circuit diagrams but I do believe in Keith's explaination and in discussions with 2005/6 CRD owners it would seem that these KJs do have the regulation done inside the alternator itself......the 2005 Circuit diagram does show that the CRD has only one wire going into the alternator called the "generator source" coming from the Front Control Module :?
Author:  thermorex [ Mon Dec 01, 2014 8:22 am ]
Post subject:  Re: Bad alternator?
Billwill, you may be correct, I admit I didn't even look in the manual, lol. I am not sure why the Crd would always charge, from the point of view of a modern alternator this doesn't make to much sense for me, but that's not saying you're not right. The "energizer" wire is there solely for the purpose of generating electromagnetic field so the alternator can charge. Could that decoupler be used to "even out" the "pulsations" from the 4 cyl engine? Of course, but it would make sense, for me at least, to be in there more for smoothing out the charge/not charge cycles, but again, I'm just talking in generic terms. I believe all modern alternators charge less than 100% of the time, and this for fuel economy purposes. Maybe somebody can confirm more details...
Author:  papaindigo [ Mon Dec 01, 2014 11:17 am ]
Post subject:  Re: Bad alternator?
For what it's worth Litens has some online information about the benefits of the type of pulley on the CRD. As to the 4 vs. 6 cylinder pulse I suspect the typical Dodge Cummins "chirp" at engine shutdown is directly related to lack of a decoupler pulley on the alternator.
Author:  flash7210 [ Mon Dec 01, 2014 1:19 pm ]
Post subject:  Re: Bad alternator?
A few months ago, when I did my glow plugs, I removed the alternator and tested the pulley by hand. When I would quickly turn the pully I could feel the clutch grab and spin the alternator shaft. When I stopped turning the pulley the clutch would release and the shaft would slowly stop on its own.
Author:  Greasey Bob [ Tue Dec 02, 2014 4:46 am ]
Post subject:  Re: Bad alternator?
I replaced my alternator today. The decoupler clutch was destroyed with parts hanging out of it. It was a lifetime warranty version and I got a new one for free. But it ruined my day. Obviously I saw it coming as it made horrible sounds and then stopped.
Author:  Rocky05 [ Thu Dec 04, 2014 7:52 am ]
Post subject:  Re: Bad alternator?
thermorex wrote:
Rocky05 wrote:
papaindigo wrote:
Most likely issue is alternator and/or alternator decoupler pulley. Check the latter at idle by looking down (may need grab a flashlight and remove plastic engine cover) the serp belt at the serp belt tensioner; if it's barely twitching decoupler is ok but if it's bouncing decoupler is bad and will eventually destroy tensioner. Otherwise have a good auto electric shop (best not start at Auto Zone as they have an incentive to "not" find a problem with their alternator) check alternator output which can be done on the vehicle.

Assuming you are buying "good" batteries (e.g. 800+CCA and a warranty period of 4+yrs) you should not be replacing them every 18 months. If you are getting 2yr warranty batteries then every 18 months is not unreasonable.



/side note. Has anyone ever experienced an alternator coupler fail in the open/ not charging position? Inquiring minds would like to know....


The decoupler name is a bit misleading. What happens is that the computer cuts the plus (the "energizer" wire for the alternator - the only thin wire that plugs on the top of the alternator - diesels have only one wire, gasolines have usually 2, the other one goes to the ignition coil) when charging is not needed, so alternator just spins without producing any electricity. When computer "senses" that charging is required, it powers back the energizer wire, which just creates a magnetic field in the alternator so the rotation of the rotor will produce electricity which will start charging the battery. When this happens, there will be a sudden mechanical resistance caused by turning the alternator rotor in an electromagnetic field -generated with the current from the energizer wire (which is not present when the energizer wire is not powered up), this is where the decoupler (which is purely mechanical - a spring and/or some clutches that is supposed to make that "shock" smoother) comes in place. So the decoupler, at least in theory, can't fail in "no charge" position since the decoupler does not turn on/off the charging, the energizer wire does that. Older charging systems had earth magnets which didn't need any energizer, they were always on, and turning the rotor in the stator that had earth, permanent magnets always produced electricity, you can't turn that off unless you stop turning the rotor.

As a side note, I am not sure how exactly the decoupler in the Crd is made, I think it's a combination of clutches (thus the red dust when the coupler goes bad) and some springs, but when it fails you won't miss it, sounds so bad that you'll definitely notice.

Oh, btw, don't mean to patronize you, just thought that a bit of detail won't hurt.


Sent from my iPhone using Tapatalk


Theromrex! LOL, I just saw this post! You and Papa give great explanations. BTW, I am an industrial electrician. I deal with many people that have no idea how electricity works. It is easier for me to dumb everything down, and give the simplest explanation possible. I just don't have that patience to write a dissertation on how an alternating current is converted into DC. Much less excitors or bridge rectifiers...

I just try to stick to the simplest determination of a problem and fix first. I usually work on multi-megawatt gensets, so please don't take my question of the coupler failing completely as an uninformed inquiry. The only diesel that I've been responsible for that is smaller than my CRD was a little hand crank start one cylinder diesel air compressor ;)
Author:  thermorex [ Thu Dec 04, 2014 9:00 am ]
Post subject:  Bad alternator?
Rocky05 wrote:
thermorex wrote:
Rocky05 wrote:
[quote="papaindigo"]Most likely issue is alternator and/or alternator decoupler pulley. Check the latter at idle by looking down (may need grab a flashlight and remove plastic engine cover) the serp belt at the serp belt tensioner; if it's barely twitching decoupler is ok but if it's bouncing decoupler is bad and will eventually destroy tensioner. Otherwise have a good auto electric shop (best not start at Auto Zone as they have an incentive to "not" find a problem with their alternator) check alternator output which can be done on the vehicle.

Assuming you are buying "good" batteries (e.g. 800+CCA and a warranty period of 4+yrs) you should not be replacing them every 18 months. If you are getting 2yr warranty batteries then every 18 months is not unreasonable.



/side note. Has anyone ever experienced an alternator coupler fail in the open/ not charging position? Inquiring minds would like to know....


The decoupler name is a bit misleading. What happens is that the computer cuts the plus (the "energizer" wire for the alternator - the only thin wire that plugs on the top of the alternator - diesels have only one wire, gasolines have usually 2, the other one goes to the ignition coil) when charging is not needed, so alternator just spins without producing any electricity. When computer "senses" that charging is required, it powers back the energizer wire, which just creates a magnetic field in the alternator so the rotation of the rotor will produce electricity which will start charging the battery. When this happens, there will be a sudden mechanical resistance caused by turning the alternator rotor in an electromagnetic field -generated with the current from the energizer wire (which is not present when the energizer wire is not powered up), this is where the decoupler (which is purely mechanical - a spring and/or some clutches that is supposed to make that "shock" smoother) comes in place. So the decoupler, at least in theory, can't fail in "no charge" position since the decoupler does not turn on/off the charging, the energizer wire does that. Older charging systems had earth magnets which didn't need any energizer, they were always on, and turning the rotor in the stator that had earth, permanent magnets always produced electricity, you can't turn that off unless you stop turning the rotor.

As a side note, I am not sure how exactly the decoupler in the Crd is made, I think it's a combination of clutches (thus the red dust when the coupler goes bad) and some springs, but when it fails you won't miss it, sounds so bad that you'll definitely notice.

Oh, btw, don't mean to patronize you, just thought that a bit of detail won't hurt.


Sent from my iPhone using Tapatalk


Theromrex! LOL, I just saw this post! You and Papa give great explanations. BTW, I am an industrial electrician. I deal with many people that have no idea how electricity works. It is easier for me to dumb everything down, and give the simplest explanation possible. I just don't have that patience to write a dissertation on how an alternating current is converted into DC. Much less excitors or bridge rectifiers...

I just try to stick to the simplest determination of a problem and fix first. I usually work on multi-megawatt gensets, so please don't take my question of the coupler failing completely as an uninformed inquiry. The only diesel that I've been responsible for that is smaller than my CRD was a little hand crank start one cylinder diesel air compressor ;)[/quote]

Great, that's why I added "don't mean to patronize you", my idea is that if this is "old news" for you, it could help somebody else. I'm not an electrician or a mechanic, I write software, but I'm curious enough about some things to determine myself digging for more info. Plus, electricity-wise, one of my best friends is an electrician, he answers all my questions and explains me lots of things.

The question is legit though, as to what makes the decoupler fail, and I'm still not 100% sure, but I'd say I'm 99% sure the cause would be clutch wear (I can't explain otherwise the all-known red dust that we notice when the decoupler goes bad) that leads to bearing wear. Maybe also that spring that's supposed to absorb the shock can also break... I should probably cut an old one to find out and post some pics...
Author:  Billwill [ Thu Dec 04, 2014 10:57 am ]
Post subject:  Re: Bad alternator?
It would be nice to see a cut up old de-coupler spring so as to see how it works......I worked on machines many years ago that had this sort of one-way clutch using a spring and on those machines the spring had to be kept lubricated!

I would like to know what would happen if these de-couplers got a spray with some Q-40 or similar.....which we are of course not supposed to do...but think about it, we start getting "red dust" ie. rust and then the assembly packs up :?
Author:  irunmiles [ Sun Dec 14, 2014 2:21 pm ]
Post subject:  Re: Bad alternator?
Just wanted to provide an update. I charged the battery, started the jeep, and the voltage across the battery read 13.2. However it started to drop after turning on the bright lights. Autozone honored the lifetime warranty and I replaced the alternator. Voltage across the battery is now a steady 14.3. Hopefully this issue is resolved, and now I can move on to the front end problem which will be a new post.
Author:  Rocky05 [ Mon Dec 15, 2014 6:34 am ]
Post subject:  Re: Bad alternator?
irunmiles wrote:
Just wanted to provide an update. I charged the battery, started the jeep, and the voltage across the battery read 13.2. However it started to drop after turning on the bright lights. Autozone honored the lifetime warranty and I replaced the alternator. Voltage across the battery is now a steady 14.3. Hopefully this issue is resolved, and now I can move on to the front end problem which will be a new post.


Good job! Happy to hear that!
Author:  TKB4 [ Tue Dec 16, 2014 10:30 pm ]
Post subject:  Re: Bad alternator?
I have a rebuilt mopar alternator to put on tomorrow .. The informative thing is that my CRD would only run about two hours with a fully charged 8 month old ome battery in daytime with no lights on, much less than I would have thought. I had to stop at rest area 10 miles from home returning from a duck hunting trip in Arkansas to charge battery with generator and battery charger to make it rest of the way. It failed on way to arkansas. I heard noise from the decoupler about a hundred miles before it went out. It makes me think there may be a short somewhere.

FYI If I remember correctly
first battery light on right dash and lightning bolt looking light on left flashes
then when voltage lowers air bag light comes on
Next parking brake light comes on
Next overhead console goes out
Next lose engine power intermittently
Next engine totally quits running
Voltage Read 10.2 volts on battery when engine quit
Author:  TKB4 [ Sat Dec 20, 2014 12:28 pm ]
Post subject:  Re: Bad alternator?
forgot cruise control goes off just before engine stops but continues working even with parking brake on
Page 1 of 1 All times are UTC - 5 hours [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/