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Discussion Starter · #1 ·
2011 Grand Cherokee Overland, 116k miles. I started my jeep, heard a loud humming noise so I shut it off. Then saw smoke rolling out under the hood. I opened the hood to see flames an smoke coming from the alternator!!! I had it towed to a shop that turned out to be too busy to work on it. I ended up installing a new alternator myself but still doesn't charge. Turns out after a lot of searching online I believe the PCM is also fried. Of course, they are on backorder everywhere, so I spent 1/2 a day to finally locate one at a dealer across the country willing to sell me one they had. I paid to have it overnighted and have to have my Jeep towed to the dealer to install and program the PCM, which I am hoping fixes the charging issue. What a joke, Thanks Chryler for yet another expensive break down on this POS. It seems every year I spend thousands of $ on repairs on this thing, each time I'm into it so deep I can't even bother to put enough $ aside to trade this thing in on something better. Never again, I've owned nothing but Jeep for 30+ years, this one broke me.

Of course there is a recall for these faulty alternators, but it doesn't cover my year or model. Who in their right mind designs a charging system that incorporates the voltage regulator in the PCM!
 

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The recall is for several lots of Alternators they discovered had defective diodes installed in them. When a diode fails they should open the circuit and result in an alternator not producing any electricity at all. These defective diodes could fail in a shorted condition, which would result in the alternator producing AC current and at crazy voltages and currents. If this happened it could damage lots of electronic equipment, the battery and even start a fire.

If you're alternator wasn't covered under the warranty, then it wasn't one of the lots that got the defective diodes.

Just because your Alternator caught fired, it doesn't mean your diodes shorted out, there are more than one way for an alternator to catch fire. But yes, it is possible the diodes shorted.

Why are you assuming the PCM is fried? What you've posted doesn't support that. Did other electronics in the vehicle fry? Was the battery damaged? If your engine is starting and running properly, which you seem to indicate, I would not suspect a fried PCM. If just the Field Control of the PCM fried, I would think there would be a code.

You just had a fire near the PCM, TIPM and relay/fuse boxes, where there is a ton of wiring. Have you inspected the wiring for heat/fire damage? The voltage regulation from the PCM is controlled by a single wire that is connected to the alternator, which was right in the middle of the fire. Have you tested the wire and confirmed it is not shorted or open?

I share your frustration with FCA. It was bad under Daimler, but since Fiat, it seems its been nothing but crisis management of just trying to move as many new cars as possible no matter what the cost to future business. They have let their dealerships sink to utterly low levels, quality and reliability it completely out the windows. Parts, Recalls, etc all one frustration after another for customers, burning their bridges for future sales. My 2011 has broken more than any vehicle I have owned in my life. My 20 year old Grand Caravan with 250k miles (the Carvan's were notorious for being unreliable) breaks less than my WK2 at half the age and mileage. Granted, I just keep the old Caravan around for cheap pickup truck duties for various projects, so it is barely driven. But still, that vehicle is a worn out junker, it should be the one breaking before the WK2.
 

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Why not put on a external regulator, I have fixed probably 10 Chrysler products in the last twenty years that had a bad body control module that way
 

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The charging systems have become increasingly sophisticated over the years. They basically do smart charging now, and that is sorta needed for the AGM battery's, not really needed. But it makes the charging system more reliable and battery last longer. That is why its part of the PCM.

Why not put on a external regulator, I have fixed probably 10 Chrysler products in the last twenty years that had a bad body control module that way
Does the external regulator just hold a single voltage? Or does it have sensors or inputs to do more? Granted its viable alternative even if it holds just a single voltage, the drawback is the battery might not last as long, you may not have a battery fully charged as soon after start, etc...
 

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Chrysler has been using the pcm to regulate charging since 1993 at least. Way before AGM batteries. I use a standard ignition VR125, same regulator that chrysler used from 1970 thru 2005. Quick and easy to install, you can do it for under $40 and best of all, the car will charge again. Even with a bad PCM
 

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Chrysler has been using the pcm to regulate charging since 1993 at least. Way before AGM batteries. I use a standard ignition VR125, same regulator that chrysler used from 1970 thru 2005. Quick and easy to install, you can do it for under $40 and best of all, the car will charge again. Even with a bad PCM
Yes, Chrysler has been using the PCM to regulate the alternator since 1993, but not the exact same way for all 28 years. The charging methods and control have changed and it changed again before they started using AGM batteries. And while charging an AGM battery is a little different than earlier battery's, as long as you keep the voltage below 14.4 volts you should be OK.

Maybe earlier than '93, I had an '88 plymouth I seem to remember also had field control by the PCM. Memory may be failing me on that.

I do agree, depending on the situation, hooking up a $40 independent voltage regulator and calling it day could be a great solution.
 

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Here is a guy selling a kit,
Thanks, I was actually searching how it is wired up because I was curious.

I thought the field control on the WK2 Denso alternator was single wire? Am I wrong on that? All I could find for wiring was a 2 wire field control.

If it is a single wire, where does the 2nd wire connect to? Positive of the electric system from the ASD relay?
 

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Thanks, I was actually searching how it is wired up because I was curious.

I thought the field control on the WK2 Denso alternator was single wire? Am I wrong on that? All I could find for wiring was a 2 wire field control.

If it is a single wire, where does the 2nd wire connect to? Positive of the electric system from the ASD relay?
I usually put a relay tapped off the fuel pump relay to provide the power to the regulator. The other wire of course goes to the field control. The relay is kinda overkill but I prefer it that way
 

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Discussion Starter · #10 ·
The recall is for several lots of Alternators they discovered had defective diodes installed in them. When a diode fails they should open the circuit and result in an alternator not producing any electricity at all. These defective diodes could fail in a shorted condition, which would result in the alternator producing AC current and at crazy voltages and currents. If this happened it could damage lots of electronic equipment, the battery and even start a fire.

If you're alternator wasn't covered under the warranty, then it wasn't one of the lots that got the defective diodes.

Just because your Alternator caught fired, it doesn't mean your diodes shorted out, there are more than one way for an alternator to catch fire. But yes, it is possible the diodes shorted.

Why are you assuming the PCM is fried? What you've posted doesn't support that. Did other electronics in the vehicle fry? Was the battery damaged? If your engine is starting and running properly, which you seem to indicate, I would not suspect a fried PCM. If just the Field Control of the PCM fried, I would think there would be a code.

You just had a fire near the PCM, TIPM and relay/fuse boxes, where there is a ton of wiring. Have you inspected the wiring for heat/fire damage? The voltage regulation from the PCM is controlled by a single wire that is connected to the alternator, which was right in the middle of the fire. Have you tested the wire and confirmed it is not shorted or open?

I share your frustration with FCA. It was bad under Daimler, but since Fiat, it seems its been nothing but crisis management of just trying to move as many new cars as possible no matter what the cost to future business. They have let their dealerships sink to utterly low levels, quality and reliability it completely out the windows. Parts, Recalls, etc all one frustration after another for customers, burning their bridges for future sales. My 2011 has broken more than any vehicle I have owned in my life. My 20 year old Grand Caravan with 250k miles (the Carvan's were notorious for being unreliable) breaks less than my WK2 at half the age and mileage. Granted, I just keep the old Caravan around for cheap pickup truck duties for various projects, so it is barely driven. But still, that vehicle is a worn out junker, it should be the one breaking before the WK2.
 

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Discussion Starter · #11 ·
Yes, I went over the wiring and nothing got hot or melted. I was checking for a fusable link or something that would cause the new alternator not to charge. I did more research and realized the PCM controls, or does the work of the regulator. I went to the local dealer and was able to corner one of their experienced techs and talked things over with him, and what had happened. He told me he has seen a LOT of this, and 75% of the time when this happens they have to replace both the PCM and alternator as a pair because one will take the other out. Sometimes yes, the wiring gets burned or melted, but this luckily is not my case. The dealer said they could troubleshoot the issue for me to confirm it's the PCM, but wouldn't get to it until the end of the month, and at $150 per hour. There aren't too many pieces of the puzzle so I'm gambling on replacing my PCM with a factory refurb and crossing my fingers. If that doesn't work I guess I go the route of an external regulator.
 

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Replacing the PCM requires the Dealer to write the VIN# to the new PCM, unless you happen to have one of the very expensive electronics tools capable of doing this. Its because of the immobilizer system, it compares the VIN# of several modules and they have to match otherwise it will refuse to start the engine. It prevents someone from stealing the car for the cost of a refurbished PCM.
 

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Discussion Starter · #13 · (Edited)
You are correct, just like when I had to replace my TIPM out of pocket at 80k miles, I have to have it towed to the dealer to reprogram. Just great, this thing has been well taken care of and not abused

52k Steering rack
65k Had to pay to replace dash because leather was all peeling up, I did get reimbursed for that
70k AC evaporator, was leaking freon
78k Motor mounts, $1200! Fluid leaked out and whole jeep would shake at idle
80k TIPM and radiator fan
89k Radiator
93k water pump
97k, Cam and lifters, had to replace lifters 3x because I couldn't get Mopars, on backorder and aftermarkets would bleed down. Finally got my hands on Mopar lifters the 3rd time.
103k VVT valve, screen came loose and stuck valve
112k Front right axle/wheel bearing
116k, Alternator and PCM
Oh and not to mention I need to carry an extra fuel pump relay at all times because I can't get my hands on the latest relay, and it's died on me a couple of times now and swapping a new relay in gets me going again.

Wonderful vehicle
 

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Discussion Starter · #14 ·
Just a follow up, I required both a new alternator and a new PCM. After replacing both it is charging again. Even tho I sourced and replaced the alternator myself, you still need to rely on the dealer for the PCM and programming regardless. Get ready for about a $1300 hit even if you do some of the work yourself
 

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Sorry you had to shell out the buck for a new PCM. My alternator failed like its suppose to, it just died and did not charge. A rebuilt alternator, installed in two hours, and I was back in business. So while I can see how an alternator failing could cause your PCM's field control to burn out, it is not a guarantee you need a new PCM if the alternator fails.
 

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Yeah my 2014 5.7 GC alternator burnt up also a year or two ago, no fire but smoke was in cabin. Happened to be very close to dealer at time so just dumped it there for yet another maxcare item.
 
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