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JEEP PCM / ECM...REPLACEMENT LESSON LEARNED

by Cat5 Cane / January 4, 2009 11:29 PM PST

A COLLECTION OF POSTS AFTER REPLACING MANY PARTS AND DOING THE MAGIC SCREW THING, WE COME DOWN TO REPLACING THE PCM... BUT FIRST....
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Good Luck
by askyward - 11/16/08 7:55 PM In reply to: SPREAD THE WORD!!!!!!!!! STALLING / NO START PROBLEMS FIXED by pla4kps
If your long joyous path to success included disconnecting the negative battery cable or disconnecting the connector(s) going into the PCM... all you have really done is reboot the PCM. All the sensors you replaced will get the credit for success until the PCM relearns its evil ways. I wish you luck, but let us know in a about a month. Most of these problems ultimately are the result of a crack/old solder joint that intermitently shorts the circuit panal inside the decades old PCM. Getting a refurb PCM is a 50/50 shot at getting someone elses bad core PCM as your $300 replacement. I would go with a new PCM... or a toyota.
dw


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Buying a PCM Replacement - New!

by askyward - 1/4/09 10:14 PM
I now have a 96 4.0L JGCL that runs great, finally. And I hope forever.
I have a "new" PCM installed after jerking around with two "refurbished" PCMs over the last 12 months.
PCMs: I dont think you can find a new/virgin PCM, anywhere. Even a friend that is the parts manager at the Jeep Dealer admitted that a new MOPAR PCM is actually rebuilt. BOTTOM LINE: If you come to the conclusion that your problem is the PCM: Only buy a "completely rebuilt PCM" with a lifetime warranty. I learned the hard way that going the cheap way is the long way and more expensive. I bought a refurbished PCM, twice. Rebuilt and refurbished, sounds the same, but its not. Regardless, when you are shopping for PCMs demand to know if the circuit board has been stripped down and all the electronics are new and tested. Bench testing an old PCM and replacing one transistor and selling it as refurbished is the norm....don't do it.
So you get my point, dont go cheap. For those that want to hear my story read on.
Decision time: Jeep Dealer or Internet Shopping. Dealer is going to be $450 plus $85/hour labor to remove PCM/flash the VIN/install PCM plus the joy of dropping it off at the dealer. You will get a MOPAR Rebuilt PCM and a one year warranty. Internet: Go cheap like me $199, +30 SH and you get a refurbished PCM already flashed with your VIN ready to plug and play. One year warranty, sweet...wrong. Two months later the PCM starts to fail. Pay another $30 SH to swap for another refurbished PCM, glad I got that 1 year warranty. 6 months later the 2nd PCM starts to fail. Now you learn that the fine print says that the value of the warranty drops 50% after 6 months. So to get my 3rd crappy refurbished PCM it will cost me an extra $100 plus ANOTHER $30 SH.(Thats $400 total so far) I wont even begin to explain the joyful process of getting your warranty honored.
REBUILT PCM: In the process of getting a 3rd PCM two key things happened: My dealer admitted that MOPAR can only supply rebuilt PCMs. The Internet PCM guy said that he could get me a rebuilt "never been in a car" PCM for $379 plus $30 SH minus a $100 credit on my refurbished crappy PCM. $409 final value. Cost me $309 + $229 for PCM #1 + $30SH for PCM #2 = $568 aargh! $229 is alot cheaper than $409 but dont do it. Plus my rebuilt PCM did come with a lifetime warranty.
PCM SELLERS: Google and Ebay will have you connected to 5 or 6 PCM ECM resellers in the US.
MINE: AutoComputerExchange.com (ACE)in Davie Florida. 888 664-8787 or 954 983-4948. BetterBusinessBureau BBB of Broward Co gives them a big fat F, yep F. If you cannot get past the sales person to speak with a tech rep, say goodbye. If the tech rep cant clearly explain the difference between a refurbished and a "start from scratch rebuilt PCM", say goodbye.
FINAL: My "Rebuilt PCM" only has a 3 month track record, not very long considering my history. But my jeep runs stronger and more confident than ever before. "Confident" seems like a wierd choice of words for an auto, But if you have had issues with a Jeep PCM, then you and I both know that "confident" is the KEY word. I wish that I had gone with the Jeep dealer a year ago. I stayed with ACE to recoup $100 from my investment, plus I finally talked with "G" at ACE and he explain that the PCM was new inside, no better/no worse than MOPAR.
*** I hope this helps. You can cross ref my previous posts, I have done it all. PCM screws, sensors, wiring, all the vodoo auto fixes in this forum. Ultimately it is the 12 year old circuit board that is at the end of its life. Its lived a hard life strapped to your firewall for 200K. I don't know why we accept the fact that the alternator, starter or water pump has a limited life. But the PCM causes a serious case of denial when its time is up. Probably because its some serious beer money, a set of tires or shocks. But if you cant drive it out of the garage, whats the point.
Cheers, dw

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Thanks you for your in-put. All of us who have gone thru your plight understand your anger. Hope everyone reading this will gain from your lessons learned and also contribute back to the blog, after they find their fix... CAT5

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keeping it fresh
by Cat5 Cane / January 12, 2009 8:30 PM PST

just adding note to keep this post close to the top of the board for slobs like me and you to read...

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I replaced ECM and still have problems
by iownherbie09 / January 20, 2009 4:10 PM PST
In reply to: keeping it fresh

Hello,

I have just posted on the thread on 97 jeep stalling and also the jeep stalling fix....and I would cut and paste my post here too, but I do not want to be flagged for spamming or abuse of the site or anything so I was wondering if you could take a look at one of those threads and read my post please? Any advice/suggestions/comments will be appreciated.

Thank you!
iownherbie09

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I went ahead and posted my jeep stall here too
by iownherbie09 / January 20, 2009 4:18 PM PST

Hello Everyone!

I thought I was the only person who owned the Jeep version of Herbie the car! It is so frustrating to have to drive around on the verge of a heart attack because every 100 feet I am sure this will be the time my car stalls again.
I have a '97 grand cherokee that is 4x2 automatic 4 cylinders. I knew absolutaly nothing about cars before this problem, except that they need gas,oil, and water; and now I only know probably what I have researched on the web trying to solve this issue so please forgive my ignorance on the subject and the lenght of my post because I cannot describe this problem in any other way.

My jeep has been stalling ( and by stall I mean it shuts off and I have to put it in neutral to start it up again) for the past few months it started out extremely intermittent and only at stop signs or red lights then it progressed to more frequent ocurrences and then it started stalling and hwy speeds and it even stalled on the HWY going at 65mph +...well that scare did it for me and I finally took it to the mechanic. That very day I thought the car was finished because now it would even rattle indicating it was going to stall and then when it did shut off it did not want to stay running...

I was advised to replace the ECM/computer after he "jiggled" the connectors to the computer and it would cause the car to shut off and he said that indicated an ECM problem. There were really no codes before except for the coil so I went ahead and okayed the replacement.

So now my car has a remanufactured ECM that was a little less than $600 plus another $200 in labor. The ECM is supposed to be ordered from a jeep dealership. The first 2 days my car ran fine and I thought the problem was solved. Although the first day it did make a sort of rattling noise which scared me for a second.

Well after one day of being parked it started acting crazy again. It shut off when I was driving at street speeds and the gas gauge indicated it had 1/4 tank gas then shot down to empty with gas light flashing then went back to 1/4 gas tank.I filled the tank and it didn't do that crazy gauge thing again but I noticed that the gauge is not marking the correct amount of gas. I filled up again and it indicated I had 3/4+ tank of gas on the gauge yet it took about 9 gallons to fill the tank!! I may not know much about cars but that seems like that gas gauge is faulty now! I was wondering if this could be linked to the replaced ECM??? My mechanic believes that it may not be related because the computer does not have to do with that, but I mean why did start happening now?

Also, the intermittend stalling/shutting off isn't as frequent as before and it now does it mostly when it is the first warm up of the day, idling, and coasting to a stop. I have also noticed that sometimes it wants to stall and the check engine light will flash and it kind of revs a tiny bit but thank God does not stop...I was wondering if anyone thinks this means the replacement ECM is faulty or needs to be reflashed? or if it just means that the ECM was never the problem. I mean I would think it had to be the problem if the symptoms mostly went away right and it just wasn't fully programmed correctly.

Also, the mechanic connected to the scanner again and it showed no codes for the engine but for the body it showed a code and he said this could mean the OTHER computer has a problem!! what the heck?! what is the other computer and what does it do, he mentioned the jeeps have 2??? I never knew this...I just want to be informed before I spend another $1000 and still end up with a herbie car...

oh and I almost forgot, May 2008 all 4 tires were replaced at a shop. Afterwards, the jeep started making a noise that seems to travel alongside the front of the car. My dad replaced the break pads at home as well as replaced whatever holds them I think because the parts were bent(?) but the car continued to make that noise to a much lesser degree and much less frequently, now it would not do it on the fwy. Before this stalling phase I would mostly drive fwy or fast streets so with the radio I wouldn't even hear the noise...horrible bandaid to the problem :(! but after reading throught this thread I noticed a post about a tire hitting some computer connections or something? could someone clarify? Could this possibly be what is happening to my car???????

THANK YOU SOOOO MUCH FOR ANYONE THAT READS THIS AND REPLIES... I greatly appreaciate your time and help..I am a broke graduate student who can tell you about cells in the body but does not know crap about this..i wished I had studied mechanic or electric engineering or something...ugh...but yeah thank you!

p.s if for some reason my mechanic reads this and the story seems familiar, just goes to show how frustrated and broke I am, not trying to completely second guess your work, just trying to help the process and solve this issue!!

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Yes... there are 2 computers
by Cat5 Cane / January 22, 2009 2:03 AM PST

Per your question... yes there are 2 computers...One is the PCM or ECM same computer and then there is a BCM, Body Control Modual, which controls guages and power seats, power windows, etc.
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just for kicks... add Gas cleaner to gas... It cleans injectors and it helped me.

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Suggest to read old post below and contact G Concepcion... Send him a reply to his post and maybe he'll respond, as to what he found and what was wrong.
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by gconcepcion - 8/24/08 8:30 PM
update, stalling still fixed, but having other minor problem

Just an update, it's been almost 2 weeks since I installed the remanufactured computer and everything is still running strong! Not even a hint at stalling!

However, i'm having weird problems with my gas gauge reading "Empty" when I first turn the car on despite having a full tank. If I turn the car off, and turn it back on, it will go back to normal and accurately tell me how much gas is left. Is there a fuel gauge sensor somewhere that needs to be replaced? Any ideas?

and the passenger side air conditioning leak into the floormats has returned after my 2 year old DIY fix stopped working. It's now leaking out of another as-of-yet unidentified area so I'll have to do some hunting around under the carpets...

One thing that i've learned about owning a jeep is that once you finally think you have a problem solved, it's only a matter of time(usually short) before something else goes wrong.

Post 265 of 327 Jeep Fixed
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Find his post and respond but remember that the Numbers change when someone adds a post.

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replaced ecm/pcm hopefully this is the fix
by iownherbie09 / February 1, 2009 9:10 AM PST

Thank you so much for the reply! the mechanic had to take back the first ECM/PCM and replaced it again. This time the second one seems to be working fine, it has been 1 week so far and I am hoping the jeep continues to run without any problems. Oh and the mechanic consulted a chrysler specialist and they told him that the ECM does control the gas gauge and sure enough with this 2nd attempt at an ECM the gas gauge problem went Away...good luck to everyone out there with this problem!

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My advice
by batvette / March 11, 2012 12:31 PM PDT

My infallible expert and educated advice is to get rid of that GC to the first sucker you can con into buying it even if you have to pay him.
I have never heard of a vehicle having such outrageous dependability issues and nobody from factory to dealer to owners can isolate an underlying fault other than the vehicle is hopelessly unfixable or it's running now let's cross our fingers it stays that way for a week or two.
It's a vehicle. It should start and get you where you need to go then shut off. It doesn't need to be this difficult.
I'm driving its competitor, a Honda Passport/Isuzu Rodeo, which was bashed for lacking the Jeep's luxury amenities and car like refinements.
Ha. It never breaks either!
Not trying to rub it in because I do feel for you. This shouldn't be happening.

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4 cyl jeeps are better scrapped
by b3sT_iN_th3_W0rLd / March 12, 2012 6:49 AM PDT
In reply to: My advice

OK let me start off this reply by saying i have a 1997 Jeep Grand Cherokee 4.0liter and i have not one of these issues. just shy of 190k miles. You get what you put into them. I had a stalling issue, i did a full tune up, distrubitor , cap, wires and 4 fire point bosch plugs. no issues at all since. dont take this the wrong way but at a mechanic the cheapest fix isnt always best. you get what you pay for and most of the time they want you to come back. a obd2 scanner starts at around 75$ depending on your area, invest in one. jeeps always make noises if you want a quiet ride buy a honda. Happy Also the 4cylinder jeep gc was only a export model.(2.5l diesel im guessing ) if your in america get rid of it, its a pos. they only made them from 96-98 for a reason. quite frankly i dont even know how you found one that wasnt a right hand drive unless it was a engine swap. which means your crusing around in a very underpowered GC. the 4.0 straight six was the best engine jeep ever made. if you wanna jeep id recomend offing your 4.7s and 5.9s for one. if you want added power you can always build the 4.0I6 into a straight 6 4.9l stroker and at nearly 350hp it will demolish any of those shitbox jeep made v8s.

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jeep issues
by asgah21 / July 3, 2013 11:07 AM PDT

I have owned four jeeps if the noise is a humming sound my guess would be a wheel bearing for the front if it comes from the rear it cold be the rear diff carrier bearings or the pinion bearings . mine has all of the above and sounds like a tank goin down the road . now the stalling forget the ecm or the body ecm start first with the crank sensor it wont show any codes and will stall out the jeep at any time moving or sitting still . the jeep will crank but not fire . the sensor is bolted to the bell housing and read off of the fly wheel in the trans u can get to it from below with a long extension and I think a 10 mm socket start there and it will stop stalling and make sure you get a mopar sensor the aftermarket ones burn out after about 6 months let me know if that helps wayne

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renewing post
by Cat5 Cane / February 17, 2009 9:57 PM PST
In reply to: keeping it fresh

just adding note to keep this post close to the top of the board for slobs like me and you to read...

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Keeping it strong with this posting
by Grand_Stalling_Problems / August 31, 2009 5:03 PM PDT

Great post I just bought my pcm from the junk yard. I paid $60.00 bucks but I learned a lesson also. I think it was junk.. I do think its my pcm again...My 2000 grand cherokee 4x4 4.7 with 112.000 miles is in the dealership right now. I cant sleep now expecting them to tell me its gonna be one billion dollars. LOL anyways.. This is a great posting. Ill get some sleep and hopefully it will be cheaper in the morning. I think I already changed most of the senors and 3 coils. It runs great you just never know when its gonna die out. I wish I had a new pcm in my hands, from what ive been reading I should buy some stock in these pcm makers. These pcm's are worth there weight in gold if you can get a good one. Ill post what the dealer tells me about my jeeps flu Ive contracted. I do believe thats the tech name for my jeeps sickness. JEEP FLU!

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2005 Jeep Rubicon (LJ) Stalling
by coloradorockscars / October 18, 2009 2:51 AM PDT

2005 Jeep Rubicon LJ 61,000 Miles (Stalling Issues since 5,7000)

My Jeep has also been stalling; the engine continues to run but when under a load (by acceleration or even just a good hill)it will often fall on it's face at 2200 RPM. I must (dive out of traffic) shut it off (or keep it under 2200 RPM)and wait anywhere from 10-30 second's and restart.
I will soon replace the PCM (with a completly rebuilt or "New") and will post my results here.
Thanks to all those before me posting their experiences and advice.

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stalling grand cherokee 2000 4.7L
by a-stedman / October 31, 2009 12:07 AM PDT

same problem.... 87,000 2000 grand cherokee 4.7L
when i let off the gas it might stall. happens 1 to 4 times a day.
so far i have
replaced the crank shaft sensor - it stopped stalling for 3 days $130
cleaned the throttle boddy free
replaced the throttle position sensor $72
replaced the idle air control sensor $132
replaced the map manafold airflow sensor $125
no luck it is still stalling. by the way i have done all the work myself. it was about 30 minutes for most parts
i just ordered a rebuilt ecu or pcu engine control unit. they program in the vin, mileage and part nbr so you gc will recognize it. $185
we will see when that comes.....
alan

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STALLING
by a-stedman / October 31, 2009 12:08 AM PDT

same problem.... 87,000 2000 grand cherokee 4.7l
when i let off the gas it might stall. happens 1 to 4 times a day.
so far i have
replaced the crank shaft sensor - it stopped stalling for 3 days $130
cleaned the throttle boddy free
replaced the throttle position sensor $72
replaced the idle air control sensor $132
replaced the map manafold airflow sensor $125
no luck it is still stalling. by the way i have done all the work myself. it was about 30 minutes for most parts
i just ordered a rebuilt ecu or pcu engine control unit. they program in the vin, mileage and part nbr so you gc will recognize it. $185
we will see when that comes.....
alan

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Did u get it fixed?
by idastsp / November 29, 2013 4:48 AM PST

i am writing you to see if you solved the issue when replacing the pcm, because father is having the same problem and he wanted to know if it fixed the issue so he knows it will fix his!!

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pcm
by UVAS123 / October 30, 2010 7:07 AM PDT

yes, ultimately on chryslers the pcms are not exactly the best, and i don't suggest refurbished, as i had some cars running excessively rich after i installed a refurbished computer. one suggestion go for a used one ranges from $45.00 (risk taker, as you only have one return, if it happens that you pick a broken pcm, to $100.00 from a regular wrecking yard. is even worth to have one known good pcm as they died without warnings on chryslers!

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1993 grand cherokee limited.
by jeepjake / November 29, 2010 2:00 AM PST

how did you know it was the computer? I replaced the distributer, plugs, wires, cap, rotor, fuel pump and all the relays. I even had it hooked up to a sun analyzer and nothing. It has a nasty miss and the fuel pump does not kick in right away i have to turn the key back and forth 5 or 6 times for it to kick in. The voltage drops when the jeep misses.

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JEEP Grand Cherokee Check Engine light and PCM issues
by fitzdicksn / February 17, 2011 10:09 AM PST

I have 3 Grand Cherokees(1994, 2004 and 2008 diesel) which we dearly love but the 2004 with the 4.0L engine (110,000 miles on it) has the Check Engine light problem. We now believe it has been fixed. It would throw codes for O2 sensors which we repeatedly changed and the code would come back after a cojuple of hundred miles, transmission codes, TPS codes, A/C quit working, engine would stumble sometimes but never stall. finally the dealership said it was the PCM. So we changed that and the O2 sensor and Trans Sensor codes returned within 4 miles of travel.

Finally after 3 days in the shop they found that the PCM wiring plug that goes through the firewall had badly corroded terminals and the voltage was flucuating. We changed the wiring plug and it is now behaving perfectly ..... at least for now. Fuel economy is back where it should be too. I haven't tried the A/C yet to see if it is working

I negotiated a settlement with the dealership as I told them they should have checked the wiring harness before changing the computer and they agreed. This vehicle spent its first 4 years in Toronto, Ontario which is a heavily salted road system. I expect this connector is likely corroded on many Eastern and Northern vehicles where road salt is frequently used.

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My Experience with Jeep PCM - Auto Module Source
by MaverickAutoGuru / February 22, 2014 5:08 AM PST

It's one of the most expensive part that goes bad quite often. I ended up buying a lifetime warranty Jeep PCM part from Auto Module Source. They programmed it and it was plug and play replacement of OEM part. Please do your research when buying a PCM, I will avoid any used PCM. Buy only Remanufactured unit with warranty. Here is the website i brought my Jeep PCM:
http://www.automodulesource.com/

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