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Discussion Starter #1
On the way home this morning I started smelling a burning electrical smell (seems to be intermittent). I was wondering if it was the blower motor. But upon further inspection the wiring to the resistor and blower motor seems to be intact. Getting voltage to the motor through all selections of the fan switch. Then I turned to the alternator. Seems to be hot to the touch(which in my years of diesel tech was a bad sign). So I got the multimeter out and did some testing open voltage on the battery was 12.7 which is within spec. At start up the alternator was 14.1 which is within spec and with all accessories running at 2000 rpm was between 14.2 and 14.3 which is within spec. The worrisome part I read was that the regulator is built into the PCM(which to me seems odd). There is some discoloration on the alternator case that would lead me to believe it is overheating. Any thoughts? I don't want to drop $180 to $300 for an alternator and find out it's not the problem but the pcm instead.
 

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Is the bearing inside the alternator gone and causing the heat? If you have the time, you should have the old alternator rebuild. I'm not sure what they charge where your from but I can get a rebuild for less then $150 all taxes in. What year? Motor? Mileage?
 

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At this point lets wait for more experienced guys n girls to reply. You can see my info in my sig. I have to assume the 3.3 has the name alternator but I don't know. I keep waiting for it to blow up but it keeps going.
 

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At this point lets wait for more experienced guys n girls to reply. You can see my info in my sig. I have to assume the 3.3 has the name alternator but I don't know. I keep waiting for it to blow up but it keeps going.
Their was 2 different alternators for the 4th gens, the 140 Amp alternator and the 160 Amp alternator. Since he has the 3.8 and all the power options including the power sliding doors and windows, I'd assume he has the 160 amp alternator. Whereas most of the vans (like mine and yours) have the 140 Amp alternator.
 

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I'd do that too but it's the family car and don't want the wife and kids stranded.


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no kids but 1 wife. Before every long tire I have my local parts store test it. I keep listening for the bearing to get loud,,, sounds okay still. Let me know if it is the alternator. I'm still hoping for you there is more advice on the way.
 

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I'd do that too but it's the family car and don't want the wife and kids stranded.


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If you will end up replacing your alternator make sure the replacement has the Alternator Decoupler Pulley, you can screw many things up in the belt system if you use a standard pulley.
 

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The alternators are made by Denso and are pretty robust. You can replace the 140 amp with a 160 amp if you want.
The 160 amp is 4868430AC (Lester 13870), and the 140 is 4868431AC (Lester 13871)

The alternator is pretty neat, it uses what they call a "hairpin stator" for the windings and uses flat copper wire

An alternator article mentioned this for these alternators:
"When these alternators are taken off for repair or replacement, they mostly need a decoupler pulley, bearings, and brushes. Their rectifiers and stators hold well and are seldom needed"

Some pics of the hairpin stator
https://www.dcpowerinc.com/dc-power-vs-competition

The regulator is indeed in the PCM, if it fails you need to replace the PCM

Here is a parts list. (Note, The Lester numbers are the univeral numbers for alternator rebuilders)
http://www.metroautoinc.com/Download/Denso Hair Pin Parts Catalog.pdf
 

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We just had our 2002's alternator serviced.

For a few months I would hear a noise, intermittently, during initial operation. Not all the time..

THEN

The battery light came on for ONE drive. Wifey was afraid.

SO

I hooked up the trusty ScanGauge to monitor operation. Also checked battery clamps and battery acid (all good).

Lastly, I flushed the AOD pulley with a cupful of alcohol. (Isopropanol alcohol, not the 12 yr old Good Stuff!) :nut:

Called the local alternator rebuilder, they quoted me $75 to replace the AOD with a genuine Litens unit. (The AODs were $60 online and I didn't have the special removal tool, so I thought that was a bargain.) They also recommended replacing the brushes for an extra $25.

So for $100 I had a like-new alternator that was load-tested.

++++++++++

BTW, the Scangauge ran a week before I R&R'd the alternator. Before, peak output was 13.5V, which I understand is typical, but the voltage would slip down to 12 during idling occasionally, and was not that steady.

After the repair, the alternator charged up to 14.0V after starting, and held it's 13.5V normal operating level within 2/10 of a volt.
 

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Discussion Starter #16
Drove to work with the multimeter hooked up to the cigarette lighter at the beginning of the trip it went up to 14.6 a couple of times but immediately drop back down to 14.2 and 14.3 for the first 10 - 15 minutes after initial start up. Then the rest of the trip it was 14.1 to 14.2 the rest of the way. So it seems as though the voltage regulator in the PCM is doing it's job.
 

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Discussion Starter #17
Maybe I'm missing something. Could alternator being hot be the nature of this particular beast? I know that it used to be that if the alternator was hot it was because the battery was discharged and the alternator fried because of that. The battery discharge has been ruled out.
 

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A noob question:

Can the 4th gen 160 AMP alternator be used in a 3rd gen?

Also, how can I tell in the bone yard if the alternator is 160 AMP or 140 AMP?
 

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Good that pjm fixed his issue. A diesel tech should know that the year and engine is important when asking such questions. Actually, it was a non-problem since one should expect a 140+ A alternator's case to run hot, given that = 2 kW output and the non-efficiency (guess 20%) turns into heat (~400W), i.e. why they have internal cooling fans. For those repeating, no need to rig a voltmeter, just buy a cigarette lighter voltmeter ($15 Amazon or cheaper HF model). I use in all my newer cars when on the road, so no surprises. Those who have driven a 1960-70's Mopar had a dash ammeter to tell you the charging status, though that caused other problems (high current can melt things).

Correct that if running 14-15 V while driving, the voltage regulator is doing its job. If the Vreg inside the PCM fails, it is simpler and cheaper to tap the wires to the PCM and wire an external one. Just buy one for a 1970's Mopar and much info on the web how to wire. Many Dodge truck guys have done so.

Can't answer wtz's new question about identifying models and wiring, but Google Images probably can. I attach a wiring schematic for my 2002. Looks like the same alternator controls as all Mopars since ~1971. They simply moved the Vreg inside the PCM. There are 2 field wires. #1 is 12 V supply (brn w wht stripe), #2 is "low-side switch" control by Vreg circuit (brn w gray stripe). Even if they changed PCM pin#'s from Gen 3, the wires at the alternator should be the same colors. They may have changed the connector, but they do that even within the same Gen and sometimes in replacement parts.
 

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