Thank you for being a valued part of the CNET community. As of December 1, 2020, the forums are in read-only format. In early 2021, CNET Forums will no longer be available. We are grateful for the participation and advice you have provided to one another over the years.

Thanks,

CNET Support

General discussion

Jeep Grand Cherokee stalling fixed!

May 18, 2007 12:44PM PDT

Found that the outboard PCM cover screw was shorting out the circuit board. Chrysler PCM p/n P56028412, s/n TEH106636023.

Short story long: I have a 96 Grand Cherokee 4.0L, 125,000 miles. Several weeks ago, I started to have stalling issues. Hot or cold, dry or wet, first drive of the day or last, it didn?t matter. The engine would cut out. It felt like it lost all electricals.
At the time it was showing an ASD relay code. Swapped the ASD and A/C relays. Same problem. I didn?t have time to look at it, so I had the dealer go through it. After 2 days and $200, they called and said it was the ASD relay, and that they put in a new one, and it?s all good. Um, ok, maybe I missed something. I?m a trusting soul, but let?s see if this fixes it. The next day the problem was back. I went back to the dealer and they basically said, ?We don?t know what it could be, good luck with that?. Now my wife knows why I don?t go to the dealer. By the way, the old relay tested good.
My turn. Being the methodical aircraft mechanic that I am, I grabbed a multi-meter, contact cleaner, and wiring diagrams. I cleaned connectors, ohmed out wires and sensors, checked for power and grounds. Everything checked good. By now, it?s showing ASD, crank sensor, and primary ignition codes. Then, with my wife trying to start it, I wiggled the connectors on the PCM. Every time I wiggled the gray C3 connector just right it would run. When I let go, it would die. So I took the connectors apart and tightened up the crimps (I don?t recommend doing this without the proper extractors and crimper). Threw it back together and BAM! Same problem. Well, time to bite the bullet and check for bad solder joints on the PCM board. I took the cover off of the PCM and realized that looking through the potting compound is like looking through Guinness Stout. But, I put it back in and hooked it up. It started stronger than ever, and didn?t even think about stalling. Yes! I figured that I finally got the connectors sorted out, so I left it over night to cool down. Got up the next morning and it started right up and wouldn?t stall even when wiggling the connectors. So I put the cover back on, put the PCM back in, hooked up the connectors, and BAM! It wouldn?t start! That was the point when my wife asked, ?How?s it going?? And I, being the methodical aircraft mechanic that I am, said, ?what the ----?? That?s when my wife turned around and went back into the house. While smoking a pack of cigarettes, I thought, ?Gee, it runs with the cover off, but not with it on.? DUH, wonder what it could be? So I backed out the two screws that hold the cover on and BAM! It started right up. Then, while it was running, I tightened the outboard screw and sure enough, it died. Yes! Aircraft mechanics love it when they can make things stop working. I installed new screws (1/4? long, factory screws are 1/2? long Torx head), and she?s been running great ever since.
Now, will this fix a bad crank sensor or idle air motor? No. But it is an easy trick to try before going to the dealer and having them throw expensive parts at your Jeep and seeing if any of them stick. Just back out the cover screws about 1/8?-1/4? (don?t worry, nothing will fall apart inside). If it fixes it, great! Spread the word. If not, use logical trouble-shooting steps. Learn the systems ? what will and what won?t cause the problem. Good luck.
As a side note, if you want to see a service manager?s eyes pop out of his head, tell him that you want your money back because your not going to pay them to trouble-shoot a design defect. It?s a glorious sight.

Moderator Note: This thread will popular has grown too unwieldy.
Please make a new post all your own from now on.
Closed as of March 23, 2018.

Post was last edited on March 23, 2018 5:04 PM PDT

Discussion is locked

- Collapse -
Picture and screws for (96...PCM)
Jan 28, 2009 5:33AM PST

Type of PCM or ECM's (same thing) change with different model cars and years...

The (2) screws that most posts are talking about are for a 96 Grand Cherokee and the PCM looks like this after you have removed the radiator reservoir and the plastic cover in front of the PCM...
http://i22.ebayimg.com/07/i/000/c3/7b/ef45_1_bol.JPG

Note: We are not talking about the 3 screws on the outside edge, that hold PCM to the firewall... We are talking about the 2 silver screws (in the middle) under where the 3 plugs, plug into the PCM connection.

Suggest to read all posts and take notes... you will find that most quick fixes, like screws, only last a short time, but it's worth a shot, if you have a pcm like the one shown for a 96.

good luck

- Collapse -
Jeep Grand Cherokee stalling fixed!
Jan 28, 2009 5:52AM PST

Thanks for the information and the picture. The PCM or Ecm on my 1996 Jeep Grand Cherokee 4.0 liter does not look at all like the picture. The one on my Jeep is less than half that size and I see the two screws in the picture.
The PCM on my Jeep is 3/4" deep, 6" high and 8" wide.
There are no screws below the plug sockets.

- Collapse -
CAJ1996, Jeep stalling not fixed
Jan 28, 2009 6:11AM PST

I must have hit the wrong button as the title states Jeep Grand Cherokee stalling fixed.
It is not fixed and I am still trouble shooting the cause.
I have a ODBll to read the diagnostics and it does not give me any readout on a problem.

- Collapse -
Codes
Feb 11, 2009 12:37PM PST

I just want to add that the computer will not show a code until a problem exists or reoccurs during a certain period of time. And after a check engine code is triggered, the computer will reset the check engine light if the problem disappears and does not reoccur during a certain time frame. I don't know what that time frame is and suspect it varies.

When you have an intermittent problem, you have to leave a code reader connected and monitor everything until the problem pops up.

Case in point: I have a 97 Wrangler that often misses during the warmup period only when the accelerator is pushed. It has done this since purchased in 2001. The check engine light never came on until a few months ago. It came on after about a week of daily to and from trips that were less than a mile. I took the jeep on a nice long drive(about an hour). Because it was already warmed up, the engine did not miss, and the computer reset the check engine light.

It still misses during warmup, but it is not big enough of a problem to troubleshoot yet.

- Collapse -
Pictures of remanufactured PCM
Jan 28, 2009 7:47PM PST

No codes? Did you disconnect the battery, if so you may have erased codes.

Yours looks different!!!... Yours might not be original OEM part

See attached? Different source of remanufactured PCM

http://search.live.com/images/results.aspx?q=pictures+of+PCM+jeep+&form=IGRE#focal=def0a060a50f7cca31990a8c5e4823a8&furl=http%3A%2F%2Fus.st12.yimg.com%2Fus.st.yimg.com%2FI%2Fyhst-21854666697846_2014_1026959


http://cgi.ebay.com/ebaymotors/Parts-Accessories___1996-1997-1998-DODGE-TRUCK-RAM-1500-2500-3500-ECM-PCM_W0QQitemZ350140520751QQddnZPartsQ20Q26Q20AccessoriesQQddiZ2811QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item350140520751&_trksid=p4506.c0.m245&_trkparms=65%3A1%7C39%3A1%7C240%3A1308#ebayphotohosting

If so read blogs? Yours might be company that others have had bad experiences with. Or Contact company on PCM? for help

Get history from last owner of what he did before selling car?. It goes on and on? good luck

- Collapse -
Picture of remanufactured PCM
Jan 28, 2009 11:22PM PST

The PCM you sent the picture of from ACR is the one I have.
I bought the Jeep new from the dealer.
I said it shows no codes because I have a ODBll and read for codes before I disconnected the battery.
The reason I believe it is the PCM is that it is intermittent. If it was the Crank shaft sensor the vehicle (I believe) would not start.
Mine starts every time. Just at times it is like it hic-ups when I am at higher speeds and then keeps going and other times when I am at a stop or slowing to a stop it will stall but restart right away.
The PCM can check all sensors but (I believe) it can't check it's self so it would not give me a code that the PCM failed.
I am not a mechanic but I have built engines for race cars and boats, that was before they came out with these computers for them.
I am thinking of getting the PCM from ACR that has the lifetime warranty. If I can fix the problem, I will keep the Jeep for another 10 years. If not my wife wants a Toyota Highlander or 4Runner. I believe she is smarter than I am so I should probably not waste any more money and go bye a new Toyota.

- Collapse -
Buying a PCM Replacement
Jan 29, 2009 2:39AM PST

taken from one of the boards and Copied and pasted for your pleasure...

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

- Collapse -
A confused
Jan 29, 2009 9:23AM PST

I believe you are saying that you bought your last PCM from a Jeep dealer(Mopar), is this correct. You also stated that it is best to get a CPM with a Life Time Warranty, is this correct. I checked with Jeep (Mopar) and I was told they only have a 1 year warranty (not a life time warranty on their CPM's). I checked with ACR and they sell a PCM that is totally stripped down and new parts put in that cost $279.00 and it has a Life Time Warranty. The cheaper ACR CPM is $179.00 or $199.00 I don't remember now but is is a rebuilt or refurbished PCM.
I guess my question is did you buy the last PCM from Jeep (Mopar) and if you did how did you get a Life Time Warranty.
Thanks

- Collapse -
confused... buy a rebuilt PCM from Mopar
Jan 29, 2009 9:16PM PST

Read it again... Askyward said...
Taken from above... and I filled in some words to make it more understanding...

I learned the hard way that going the cheap way is the long way and more expensive. I bought a refurbished PCM, twice, then bought a 3rd PCM that was rebuilt from ACE with a life time warranty

Rebuilt(Replaces a parts with new parts) and refurbished (fixs just the broken part and resells it), sounds the same, but its not.

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... You will get a MOPAR Rebuilt PCM and a one year warranty.

Buy it on the Internet: 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 S and H to swap for another refurbished PCM... 6 months later the 2nd PCM starts to fail. So to get my 3rd crappy refurbished PCM it will cost me an extra $100 plus ANOTHER $30 SH.(Thats $400 total so far).

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.

I bought 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.

FINAL: ********* I wish that I had gone with the Jeep dealer a year ago... Instead, I stayed with ACE to recoup $100 from my original investment,

*** 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.
Cheers, dw

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

OK, I'm done ... good luck.
Cat

- Collapse -
Buying PCM
Jan 30, 2009 9:29AM PST

Thanks, Cat5 Cane
Prices from Chrysler, Mopar (remanfactured PCM) $519.48 and $125.00 core charge which they will refund when they get your old PCM. 1 year warranty or 12,000 miles.

Price from Kragen Auto (remanfactured PCM)(not refurbished) $250.00 and $100.00 core charge which they will refund when they get your old PCM. 1 year warranty.

Price from Auto Zone(remanfactured PCM)(not refurbished) $224.99 and $85.00 core charge which they will refund when they get your old PCM. 1 year warranty.


Price from All Computer Resources store. 1-866-699-5230
(remanfactured PCM)(not refurbished) $289.00 and no core charge on old PCM. Lifetime warranty.

Just info for you Jeep owners on what I have found out about PCM's and the different prices for remanufactured, not refurbished.

I thank Cat5 Cane for all the help I have received.

- Collapse -
think you fixed mine!
Feb 14, 2009 3:46AM PST

I have a 96 JGC limited with 4.0, 109000 miles. I had the same problem... stalling when ever it wanted too. Would run great for days and then would stall 10 times in one day. I have replaced the crank sensor, and put in a new ignition pick up. No change. Today I backed out the cover screws on the computer and put in some shorter ones. Drove it all afternoon and could not get it to stall. Thanks !

- Collapse -
Stalling fixed 1998 Jeep Grand Cherokee
Feb 14, 2009 7:51AM PST

It's been 6 weeks since my husband followed your suggestion and backed the screws out of the PCM and cut them off and it's running good. I feel safe driving it again. Anyone that hasn't tried this should. It was a cheap fix.

- Collapse -
For Now
Feb 14, 2009 9:49AM PST

The screws you backed out/replaced hold a connector together inside the PCM. You simply moved the connection inside to a place where it no longer stalls. For it to be stalling because of a condition with this connection, it most likely has some broken solder traces or corrosion inside. Some people have said on this board that the screws are shorting something out. To that I say balderdash! Those screws go into a plastic housing on a connector. It may have negated the problem, but the cause still exists. I wouldn't depend on this fix to last, although some have. With some luck, it won't come back. Try this: lightly tap on the PCM after a cold crank. If it doesn't die, you may have a somewhat reliable vehicle.

I finally fixed mine with a used PCM.

- Collapse -
Stalling Jeep Grand Cherokee
Feb 14, 2009 1:00PM PST

The screw thing is just a temporary fix.
My 1996 does the same thing and mine does not have the screws that you can back out. It's a PCM problem. The Jeep PCM's may have a flaw in manufacturing. Also Chrysler had a recall, I believe it was called E22, it was to reprogram the computers. They may have messed up the computers because of the recall. My Jeep has the solid steel PCM and what I did for a temporary fix is take the three screws that mount the PCM and put heat shrink tubing on them and then use plastic washers under the screw head. This is a temporary fix to keep the computer from grounding out until I can get a remanufactured PCM. If you do buy a PCM get a remanufactured "not a refurbished"
A company in Florida named ACR sells them for about $289.00 with a life time warranty.
Just type in the subject line, Jeep PCM by ACR, and it should show the company.
I also filed a complaint with the National Traffic Safety Board as a safety item that needs to be recalled by Chrysler. Everyone that has this problem should contact them. It's the best insurance I know of incase you have an accident you may have to go after Chrysler in a law-suit.

- Collapse -
Stalling Jeep Grand Cherokee
Feb 16, 2009 12:52AM PST

It is the "National Transportation Safety Board" to contact for Jeep stall problems not the National Traffic Safety Board.
Sorry

- Collapse -
Very strange.
Feb 15, 2009 8:42PM PST

Ok, so I have a problem with stalling too. I drive a 98 ZJ 5.2 V8 Limited and it is generally in good condition. Recently though I have had a problem where to get it to start I either have to crank it for 5 seconds solid or turn the ignition 4-5 times to get it to start 1st time. After it has ran for a while, I can shut it off then start it up again within around 5 minutes and its ok, if I leave it longer than that I have the same issue of prolonged craking or tickling the ignition. Also recently it has started not goiong into reverse straight away, I either have to pull foreward a little or put it in reverse, put my foot on the brake and get it up to around 1000 revs to get it to force into revrese, its also slipping from 2nd to 3rd gear (auto). The last thing is the stalling, it mainly does it in reverse at low speeds when turning, when it does stall it will reset the info console and my cd player goes back to standard settings, every now and then it will also feel like its begining to stall when slowing down to stop.
I have changed the fuel pump twice, the plugs, wires, Crank sensor, battery twice, used fuel line cleaning additive and now I think it may be this screw problem, just want some more opinions before I go changing un-needed stuff.
Thanks, Tony.

- Collapse -
Strange... check your sensors
Feb 15, 2009 10:47PM PST

Yours sounds like it is more of a electrical/transmission (sensor) failure, then an engine failure (but the coil and plugs or injectors could come into play)... throw in a heavy dose of Lucas gas treatment to clean injectors.

I'm not a mechanic but have been here, it seems forever...

Check diagnostics codes before disconnecting battery... then disconnect the PCM plugs (remember the order), clean the tips with CRC electronic cleaner, let set for 2 hours, then reattach the PCM plugs, then the battery... thinking it should erase the codes and car might work properly for a short time until the computer resets to the information from the sensors, if bad... it will go back to screwing up after one hour to a weeks time.

two sensors come into play... Camshaft position sensor and the crankshaft position sensor. I went on line to auto zone directory...
http://www.autozone.com/az/cds/en_us/0900823d/80/04/ac/f1/0900823d8004acf1/repairInfoPages.htm

Crankshaft Position Sensor Operation:
A magnetic or hall effect sensor that provides the computer with the engine speed and crankshaft position so proper injector sequence and ignition spark can be determined. It allows the ECC or PCM (engine control computer) to change injector openings as the engine RPM changes. It also signals the coil packs to fire the spark plugs.

Camshaft Position Sensor Operation:
A magnetic or hall effect sensor. It sends a signal to the computer relaying information about shaft speed, position and acceleration or deceleration. This information determines when the fuel/air mixture needs to be ignited and how much mixture is needed for the engine.

Go to site and read How to... Inspect, test and service... Lots of good info

JMO... Sensors are critical keys to running right and to buy Jeep sensor parts... not auto zone imitations.

Just an after thought. If still not fixed...By the way... also check/replace transmission filter and check Trans oil level


After you fix it... come back to tell everyone your answer to the fix... Be complete for the next guy...

That's all I got... good luck!!!

cat5

- Collapse -
1997 jeep grand cherokee 4.0 and the stalling issues
Feb 20, 2009 3:38AM PST

my wifes 97 gc has been stalling these last 2 months,ive replaced the fuel pump,crank sensor,coil,battery,pcm,plugs,wires,distributar,pick up,cap,rotor,idle control sensor..it would run a day or so great,then start spuddering,then eventually stalling..im at a loss here now,ive sunk over 2k into it,with the same results,and it sems from the posts ive read,many people have experinced the same thing,i did check the pcm to see if it was seated right,it has a plastic case,with the screws placed in a plasted clip type thing to the fire wall.sometimes the check engine light comes on,then go off,the reading it would give is multible misfire,even after i replaced the entire distributar cap,and conponants,with new plugs and wires..can someone please give me any suggestions that i havent tried that may work,when it does run right,it runs great..

- Collapse -
PCM ?? to Billy the Jeep
Feb 20, 2009 4:03AM PST

Hey Billy, Looks like you have done everything. I would ask yourself about the PCM. You listed the PCM as something you replaced. Well actually this is a really big deal... just what exactly did you replace it with??? Please read the posts about buying a PCM. You need to have bought a completely rebuilt PCM... not a refurbished PCM. I hate the words rebuilt and refurbished, they are so similar, but SOOOO different. If you replaced it with a refurbished one, your problems will likely remain no matter how much $$$ you throw at it. Again... please read the posts about Buying a PCM. **** Luck, Dave

- Collapse -
1997 jeep grand cherokee 4.0 and the stalling issues
Feb 20, 2009 10:05AM PST

i would like to thank the responces ive recieved on my stalling question,as far as the pcm being installed,its a remanufatutured pcm that a mechanic installed back in early january..right after the issues started with him thinking it was the fuel pump at 1st..then the crank sensor,coil etc..however im curious as to what would cause it to have an issue of multible misfire,i neglected to state in my 1st question,that the 1st time the check engine light read multible misfire,after everything was changed,distributar,wires,plugs..etc.it popped on again saying misfire in plug#5 ,after resetting,the check engine light stayed off a few days,then on again,just saying multible misfire again..mechanic reset again,days later,misfire in plug #3 and plug #5..so i have no idea as well as the mechanic thats been monitoring this is baffalled..

- Collapse -
1997 jeep grand cherokee 4.0 and the stalling issues
Feb 20, 2009 12:18PM PST

I believe you said that you changed the distributor cap, new rotor and plugs and plug wires.
Did you change the complete distributor. If you are useing a mechanic to do the work he/she should have checked the cam sensor which is built into the distrbutor. Normally if the cam sensor is bad it will crank but not start.
Have you checked to see if the wires are pushed down to make good contact with the plugs. With the problem moving around like that it sounds like the plug wires are not making good contact with the contacts in the distributor cap or the plugs.
Just a thought, I don't know if dirty injectors would cause a missfire. Common sence says it might if it's not getting the proper fuel. Just a thought

- Collapse -
1997 jeep grand cherokee 4.0 and the stalling issues
Feb 20, 2009 8:56AM PST

Did you replace the Idle Air Control Valve "Sensor". They cost about $35.00 at Autozone and takes about 20 minutes to change. You will need a Torx 20 socket to do this.
Did you remove the air intake hose and clean the throttle body. This should be done when you replace the Idle Air Control Valve "Sensor".
They sell a cleaner that will clean this area called Throttle Body Cleaner. Be careful with it and wear safety glasses. When you start the Jeep after using the cleaner it may be a little hard to start and run rough for a couple of minutes until the cleaner burns off.

It sounds like you have done all the rest. If you replace the CPM, buy a remanufactured one. Don't by a refurbished. I included a company in Florida that has them.

I found them by typing in the search line, 1997 Jeep PCM by ACR. "Allcomputerresources"

This a different company than the ACE company.

A company in Florida named ACR sells them for about $289.00 with a life time warranty.
Good luck

- Collapse -
1997 jeep g/c 4.0 spudder and stall issues
Feb 27, 2009 8:19AM PST

i have one more question before i decide to go with a remanufactured pcm as suggested...i havent really been messing with my wifes jeep in the last 2 weeks,being that my 94 jeep g/c needed front end work,but now i can focus on hers more now,my question is this,each time the check engine light comes on it would flash code 43 (multible misfire) in which the last diagnostic check that was done said it was plug #5 and plug #3,now i have replaced everything the distributar,and cap,rotor pickup ,plugs,crank sensor,coil etc.. today i ordered 2-New,not remanufactured fuel injectors to replace the ones in port #3 and #5..do you feel that i have possably done the right thing..cause i beleave the last alternative and costly thing is by replaceing the pcm..what will happen is it will start fine(cold)..it will run approx.. 10 mins or so,when fully warmed up then either shut off or when driveing spudder..there was one occasion were i was driveing pushing on the peddle and it was running ,didnt stall but was like it was coasting,after pumping on the peddle a few times as i coasted,it would just start going again without haveing to restart it..jeeps ,gotta love them..lol

- Collapse -
97 JGC PCM failure
Feb 27, 2009 9:21AM PST

The PCM failure around this Forun topic does NOT post a failure code. The PCM failure results when the battery voltage into the PCM is interrupted by a problem inside the PCM 'A' connector. It's the same as turning the switch off -- no code generated. THE BEST TEST to determine if this is A problem in your case is to press the top DRIVERS SIDE of the PCM HARD toward the firewall using your thumb. If the engine sputters and or dies, then your PCM is suffering from the failure this forum topic covers. CONVERSLY if you force the top DRIVER's SIDE of the PCM toward the Radiator the failure will generally be much less. (NOT A FIX JUST A DIAGNOSTIC TOOL) I'm talking about moving the pcm by 1/2 inch or so.

The problems you have mentioned are NOT TYPICAL for the PCM failure and you likely have other issues as well, even if you do have the PCM issue. Of course it is remotely possible that you have different PCM issues, but that's unlikely. Except for the issue referred to above these PCMs are generally dependable. Read through a lot of the replys to this forum and throw out all of the voo-doo, using common sense, and there are some good suggestions. I have posted several replys that are very informative.

As to your specific misfire issues, may I suggest that you do a compression check on the offending cylinders. Also, look under your hood at night, in a dark area for sparkplug wires that are arcing. A $10 set of new wires has solved a lot of 'major' problems. Cylinder and valve carboning could aalso be an issue. Finally, remember that the PCM failures that this forum topic addresses usually occur at high mileage, mostly above 150,000 miles, although some failures have occurred sooner, possible because of driving over bad, rough or bumpy roads. In other words, it is a VIBRATION related failure. Read some of my other posts relative to replacing the PCM if you decide to do so. There are some things you need to be aware of when shopping for a replacement.
Regards,
Jim

- Collapse -
1997 jeep g/c 4.0 spudder and stall issues
Feb 27, 2009 9:34AM PST

My Jeep never acted like that. Mine would shut down or stall when I was sitting at a stop sign or light or driving very slow. It would start right away. Sometimes when it stalled while I was moving I would put it in neutral and start it right up and keep going.
The only time mine gave a misfire was when I changed the distrubitor cap and got two plugs in the wrong hole. I got the problem straightened out and then reset the check engine light. I did have a couple of hard starts in about 6 months but never figured that one out. Sounds like you are going in the right direction. I don't know if all fuel injected vehicles have this same problem. I did some research on the Autozone web site (www.autozone.com/home.htm). It stated (something like this)that if you change the PCM it may stall or stumble until it figures out how you drive.

- Collapse -
Computers are Dumb
Feb 27, 2009 12:35PM PST

Hey Guys,

The PCM is a computer. It never 'LEARNS" anything. It is programmed to do what it does and that's all it ever does. It works the same way the instant it has power applied and then responds in a preprogramed fashion to the input devices feeding it. And, with the exception of rare failures, caused mostly by mechanical stress, they perform their job well. It's the signals feeding it, and the devices it controls, that cause almost all of the problems. The only exception is that it does store faults THAT OCCUR WHEN THE COMPUTER HAS ignition POWER APPLIED. Reset these fault codes by disconnecting the NEGATIVE battery cable for two minutes or more.

- Collapse -
Computers are Dumb ?
Feb 27, 2009 1:15PM PST

The information below is from Autozone web site. It may be correct and it may not.
Autozone is one of the top auto parts stores in the USA.
Engine Control Computer




Inspect | Test | Service | Replace

CAUTION
If you remove and repair a ground connection, be sure you reconnect it to the same place. Do not change the length of the wire.


People who work around sensitive components sometimes wear a ground strap attached to their wrist.
You can eliminate the static electricity by touching ground before you touch a computer.
Do not take the computer out of the container until you are already in the front seat.
The computer is rarely the cause of problems in the fuel system. When it is, the parts are not repaired. The entire unit is replaced.

Remanufactured computers are widely available at a reduced cost for popular makes of cars.
Be sure to check the power and ground circuits before replacing a computer.

Electronic instruments can be damaged by excessive voltage, heat, moisture, or vibration, so computers are usually mounted in the driver's compartment.

Other times they are located under the passenger seat.
Newer computers are designed to dissipate heat more quickly. Some of these are installed in the engine compartment.
To be safe, pull the computer fuse before unhooking its connectors.
To remove the unit:

WARNING
Disconnect the negative battery cable. Electronic Control Computer removal procedures vary according to vehicle make and model. Consult your service manual for the procedure.


If necessary, remove any plates or covers.
Disconnect the wiring harness.
Unbolt the module from its mounting.
Some computers have a replaceable element call a programmable read-only memory (PROM).

On some cars the PROM is replaceable. Courtesy of General Motors Corporation, Service Technology Group.

The old PROM is installed in the replacement computer. Other later model computers have electronically erasable (EE) flash PROMS. These are programmed electronically, either in the dealership or by telephone modem from the manufacturer.

To replace the unit:

Bolt the module to its mounting. Torque the bolts to manufacturer's specifications.
Connect the wiring harness.
Reinstall the kick plate or other cover.
After replacement of the computer or when a battery has been disconnected, poor driveability and performance can result until the computer relearns the best driveability settings. Hard starting, high idle, stumble, and stalling are possible symptoms.

- Collapse -
Symantix, it "learns"
Apr 26, 2009 5:02AM PDT

The PCM senses changes in the engine behavior based on the signals it sends to the engine (fuel & electrical) and the feedback it receives from various sensors. If the results are outisde of the regular operating tolerances, it sends new instructions to compensate, rinse and repeat.

So when people are saying the PCM learns, they mean the PCM is adjusting itself based on the data it is receiving. For instance, you can replace a bad sensor, such as an O2 sensor, and the PCM will "know," or for those of you scared to personify a computer, the PCM will "acknowledge the change of data compared against models programed at the time of manufacturing."

Don't worry about your Jeep becoming the next "Carrie." Sleep tight.

- Collapse -
Billy's Misfire
Feb 27, 2009 8:11PM PST

I feel your pain. Most of the replys to your post seem to be giving you great advice. I would echo one comment about the camshaft sensor, it cleared up some of my problems when I was getting misfire codes. I think you said you got a new distb, and most come with a new Cam sensor included in the distb. In fact the cost of the cam sensor is just a few bucks less than an entire new distrib at Autozone.
You mentioned that the problems surface after the car warms up. That reminded me of when I replaced my two O2 sensors that screw into the exhaust system. I had read in my repair manual that the PCM disregards those sensors until they reach operating temp and then make timing and mixture adjustments. I doubt that these sensors are the villan in your Jeep, but I just wanted to pass along that I got an instant 3 mpg increase!!
Its amazing how smart these PCMs are. How they learn to vary their outputs based on sensor inputs.(Just teasing Mr MCCain just a little bit) Happy

For me, replacing my PCM with a truly rebuilt PCM was the turning point. I now have my reliable ZJ back once again, and this forum has been a great source of advice and direction. Good Luck!! Dave

- Collapse -
I've loosened the screws.......
Feb 28, 2009 3:58AM PST

time will tell if this is the fix I've been looking for on my 1997 JGC. Can you explain the new screws/washers fix? Thanks in advance for your assistance.