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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

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Reply to SPREAD THE.......
Nov 15, 2008 10:31AM PST

So you know, this is old news, buddy. It's been circulating for a while, and while the trick does "something", it's not the cure. It made my Jeep run great for about 5mos. then all problems, and more came back.
I solved it by buying a Toyota!

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at least
Nov 15, 2008 11:21AM PST

you made a good choice we built a bullet proof forrunner that goes any where and are in process of swapping our suzuki samari axels out for toyota's are you going to lift it??

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at least
Nov 17, 2008 6:19AM PST

It's a Tacoma 4WD and has a lift kit. It's definitely an all around useful vehicle and I have nothing but confidence that it will start and run every time!

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Good Luck
Nov 16, 2008 11:55AM PST

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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97 JGC 5.2l major problems
Dec 11, 2008 6:37AM PST

I'm in the same boat as a lot of you but I have the 5.2l and the majority of you seem to have the 4.0l. Once my truck gets up to operating temp I will loose power, rpm's drop to nothing and it starts to knock, backfire, something like that. I've replaced the PCM, crankshaft position sensor, cam sensor, temp sensor, cap, rotor, plugs, wires. I'm running out of options. Has anyone had this problem with the 5.2l? Thanks

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Major problems
Dec 11, 2008 11:02AM PST

Nightmare...

I might be way off base but the Catalitic converter, if clogged could shut down the engine. From memory it is blue in color when bad, caused by rich fuel mixtures or it could be the 02 sensor that plugs into the converter... is defective and sending wrong info to the PCM/ECM. If you have already replaced the sensor, then check the 4 wires to see if broken at connection.

Remember that the PCM will always try to do the opposite of what it receives from the O2 sensor. When the O2 shows lean, the PCM goes rich, and vice versa. When a lean exhaust signal is not caused by an air/fuel problem, the PCM does not know what the true cause is and will enrich the mixture in response to the signal. This may make the engine run worse than it did to the point of choking it and shutting itdown when it is hot.


Back to the converter...
At times the catalytic converter can become plugged because of the use of leaded fuel in the engine. The honeycomb core will disintegrate. Use the following procedures to inspect the catalytic converter.
Check to see if their is leaded fuel in the engine. Also check to see if the restrictor ring has been removed from the fuel inlet. If leaded fuel has been used or if the restrictor has been removed, the catalytic converter will need to be replaced.
A rotten egg smell is often produced by vehicles that have a catalytic converter. This odor is generally caused from too rich a mixture in the carburetor. If this smell persists check the carburetor adjustments or try using another type of fuel to eliminate the odor.
Pellets coming out of the exhaust indicate that the catalytic converter is damaged internally. Replace as necessary.

There are many ways to test a catalytic converter; one of them is to simply smack the converter with a rubber mallet. If the converter rattles in the interior, it needs to be replaced and there is no need to do other testing. A rattle indicates loose catalyst substrate, which will soon rattle into small pieces. This could be called a test, but it is generally not used to determine if a catalyst is good.

Converters are good for about 80,000 miles if o 02 sensor is working properly.

Info gotten from Auto Zone... http://www.autozone.com/az/cds/en_us/0900823d/80/05/03/74/0900823d80050374/repairInfoPages.htm

Again this is a stab in the dark... and to ask your mechanic

Good luck

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Major Problems
Dec 12, 2008 3:22AM PST

Cat5, Thanks for getting back to me. The cat checked out fine, no rattling inside, and I haven't gotten any codes. I should have mentioned that earlier. The one thing I'm leaning toward now is my ingnition coil. Someone had put an MSD ignition system on there. Cap, Wires, and Coil. I've already replaced the cap and wires. I went online to check the resistance of that coil and the site says the secondary should be 13,700 ohms and mine reads 14,080 ohm. I know when it's off a little it should be replaced. I checked a few of my plugs and they don't seem to be damaged by preignition or discolored from a weak spark. My only hesistation in replacing this is that my problem is at operating temp, and I don't think the coil would be affected by temp. It either has a good spark or not, right? Thanks again for any help you can give me.

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coil failure
Jan 14, 2009 8:40PM PST

This may sound silly, but it is true.

Years ago I had a 77 Triumph that suddenly began dieing everytime the motor got up to operating temp. I could not figure out the problem and went too my father for help.

He suspected the coil. I told him it didn't make any sense that the coil would fail when warmed up. He said, "let's test it."

He wrapped a wet rag around the coil. I started it up and the car ran until the rag dried out. Sure enough the coil failed every time it got hot.

So yes, It is possible.

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loose power, rpm's drop to nothing and it starts to knock!
Feb 6, 2009 3:52AM PST

Hello,

I have the same issue and have been trying to figure this out for years; I was told it's the crankcase position sensor. At the present time I haven't replaced the sensor. Have you resolved your issue? If what finally was the fix?

Brian

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2003 Jeep Grand Cherokee Laredo
Nov 16, 2008 10:08AM PST

We have the vehicle listed above and developed Hesitating problems coming down the interstate for the past few weeks. Most of the time we can pull off the interstate and continue to drive through town with no problem. I am not getting an engine light and have already replaced the fuel filter. At "in town" speeds it seems to do fine. Just at highway speeds is when we notice it hesitating badly enough where you have to pull off to the side. The vehicle does not quit completely just looses all power. Any help with our situation would be greatly appreciated.

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stalling
Nov 16, 2008 10:23AM PST

"i have ( HAD ) a 97 cherokee with a 4.0 that's not getting any spark. i have replaced the coil and checked to see its getting power (my test light will light up on GREEN / ORANGE and when i flip the tester to + i have ground on GRAY / WHITE (just not while cranking) i visually inspected the cap and rotor / cleaned all contacts with sand paper (as well as all relays under the hood) and checked injector pulse. all the gauges work on the dash and the info cluster. all the fuses are good under the hood and in the vehicle. the fuel pump kicks on fine. i was told that if the crank sensor is good then the 3 wires should test 1 as a ground 2 should have 8 volts and 3 should have between 0.3 volts and 5.0 volts but when i tested it with my volt meter i was getting between 5v and 0.3 v on one wire and between 3 and 4 volts on the other so i replaced the crank sensor because it should have 8 volts on that wire (but it didn't solve my problem). so i have also pulled the codes ( key on key off key on key off key on and count the blinks of your check engine light between pauses, if you have a digital odometer it will tell you the codes) and they are reading 12_54_55. 54 being the cam sensor which is inside the distributor on this model and year jeep aka sync signal generator and its called the IGNITION PICK UP COIL at your local parts store, and swapped it out then i disconnected the neg. batt terminal and removed the coolant reservoir and pulled the 3 plugs from the pcm checked the terminals and tested the gray / white wire (-) from the pcm to the coil itself to make sure it wasn't damaged THEN I FOLLOWED THE INSTRUCTIONS BELOW AND now i start and run beautifuly. WHAT A PAIN IN THE BUTT!! and this is the link to a jeep site that explains your vehicle sensors and how they work. good luck

http://www.jpmagazine.com/techarticles/engine/154_0608_1987_jeep_wrangler_xj/ind- ex.html

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.

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1999 GC Laredo stalling...
Nov 27, 2008 2:59AM PST

I have a 1999 GC 4L 120K that stalls. Replaced fuel pump, but still stalls. Sometimes I wait a few minutes and it restarts .
Now I found this forum (praying it'll help)
I read alot of info on 96 GC, but I think my 99 is alittle different. PCM has torx bits far passenger upper left & lower left (not directly below the connectors).

Could the PCM screws be my problem?? I have a crank sensor I can put it, but waiting for a response first (maybe save the $50 if I can return)

I don't have "Check Engine" lit, so I don't expect it's a sensor.

I did reseat the PCM connectors & relays/fuses in the fuse box by the battery.

Anything else to try??

BTW - Sweet forum!! Nice to find a place for "backyard mechanics" to trade war stories (and hopefully save $$)

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Fixed by replacing Crankshaft Position Sensor!!
Dec 7, 2008 10:51PM PST

Just a follow-up to my '99 GC Laredo 4.0L w/120K stalling:

I reseated the fuses & relays under the hood, but still stalled.
No "Check Engine" light, but I did turn the ignition ON, OFF, ON, OFF, then ON. The digital odometer flashed a P0320, which per the Chilton manual is the Crank Sensor (even though no Check Engine light).

If you need to change this sensor, Good Luck!
I used two 6" extensions with a swivel in the middle to get to the 7/16" bolt, but I did get it. You'll have to lay on the engine to get your hand back to the sensor. The wire connector is on the passenger rear of the engine.
Snug the 7/16" bolt, but no too tight (the plastic sensor might crack)

Anyway, the CPS is replaced & doesn't seem to idle as rough as before.

Just took it's first major trip since fixing this & it ran great!!

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RE:2003 Jeep Grand Cherokee Laredo Stalling
Apr 14, 2009 6:25AM PDT

Did you ever fix your issue or find your problem with your 2003? I'm having the exact same problem with my 1999 Grand Cherokee. Stalls at interstate speeds only, and it's very intermittant. Granted I have 306,000 on my 4.0 but it still has full power and hasn't given me a lick of trouble until this weird issue. It will idle all day and drive around town all day, hit the interstate at 70+ and it stalls out. Yesterday it drove an hour and a half on the interstate with no issues. This morning it wouldn't drive 3 miles without stalling. As soon as I got it onto the side roads driving under 40mph no issues... No error codes, tried swapping ASD relay and the A/C clutch relay but still same problem.

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2003 Jeep Grand Cherokee Laredo Stalling
Apr 14, 2009 7:25AM PDT

My 1996 4.0 liter GCL did a lot of what yours is doing. I tried all the trick things and none worked. After 6 months and a final stall on a very busy street in So. Cal. I had it towed. To make a long story short. As the tow truck showed up my Jeep started. I still had it towed. I was going to tow it to a Jeep dealer. The tow truck driver knew of a person that works on Jeeps and was less expensive than the Jeep dealer. After informing the mechanic of all the things I had done the mechanic said it was the Crank Position Sensor. He changed the sensor and I still had problems so he ordered another sensor. Same sensor an OEM part but they were about .10 of an inch different in length. The crank shaft sensor has to be no more than .07 of an inch from the crank area from which it is taking it's reading and no closer than .03 of an inch. They sell a spacer that you are to put on the end of the sensor. The spacer is .05 of an inch thick and when you put the sensor in, the spacer is to just touch the rotating device it reads from. The spacer is made of paper and will rub off.
I had my Jeep repaired three week ago and have put a lot on miles on and have had no problems. This worked on my 1996, hope this info helps. Just for your info. I changed all the other sensors myself and cleaned the throttle body, plugs, rotor, dist. cap, new plug wires, new fuel filter. It would run better after I did each item but would still stall. I did not change the Crank Position Sensor because on a 1996 GLC it is very hard to get to.
I was told many times that a vehicle will not start or run if the Crank Position Senor is bad. This is not true. It may start and then it may not start, it may run for a long time and then stall when you least expect it like on a freeway or busy street. Good luck.

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96 JGC stalling / no start
Dec 16, 2008 1:54PM PST

Hi, I have 96 Grand Cherokee (in Australia ) and I was looking behind the reservoir for the PCM to do the screw fix. However it seems that its on the opposite side next to the brake booster.

I have taken a photo, can anyone tell me if this is it?
Also I cant see the 2 screws. Are they behind the black plastic mould the plugs sit on?


http://i11.photobucket.com/albums/a193/heath1/P1010547Medium.jpg

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Down Under Mate
Dec 16, 2008 3:15PM PST

Its cuz you all drive on the wrong side of the road mate!!!. Yeah thats the PCM in the picture on the right side of the vehicle just like all of us. Its funny how the brake resv and the coolant resv are on opposite sides depending on which side of the car the steering wheel is on (not funny except how one persons discription in the US would be totally wrong to you down under.)
To get to the point. The screws on your PCM are different than the ones of the bloke that began all this talk about the magic screw fix. Yours are on the corners and they hold the face plate on. I say this because there are no metal tabs around the perimeter that are bent over to hold the face plate on. The screws you have read about, are very close to the lower/outer edge of the grey and black wire plugs. Those screws connect to the circuit board and the theory was that if you reduce a little pressure on them the circuits will flow correctly.
Besides that the PCM should be the same. Current and sensors in... Current and commands out. Read all the posts and confirm the basics: ASD and Fuel relays are good. The cam and crank sensors are good, and the coil thru plugs are sound. You can test all these without buying new ones. See if an OBD scanner detects fault codes, or use the onbord code check by moving the ignition key to on/off, on/off, on and wait for the codes to flash on your odometer. All of this assumes you have a basic $15 repair manual, and a $10 voltmeter. Also, and THIS IS A KEY POINT: keep in mind every time you remove the negative battery cable to trouble shoot or replace a relay (or shorten screws) or a sensor... YOU ARE ALSO REBOOTING THE PCM. If the PCM is what is bad, the reboot will temporarily fix the PCM and appear to solve your problem. Most of us think that the sensor we replaced just fixed the problem, money well spent! But beware, the faulty PCM will relearn its fault code and the car stalls again after 2 days or two weeks, money wasted. I have done all of this. I have bought a rebuilt PCM twice! I am now happy with a COMPLETLY REBUILT PCM, ALL NEW INSIDES, NEVER BEEN ON A CAR. If you get to the point where the PCM needs to be replaced.. DO NOT buy a reconditioned PCM. Buy one that has been completely... completely rebuilt inside, because most of these PCM stores take YOUR Crappy PCM that you turned in as a core, dust it off, bench check it, spray paint it and sell it to the next desperate JGC owner. Believe it.
Time for a Fosters... good luck. DW

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Down Time
Dec 16, 2008 10:19PM PST

Asky... Great information.

Have spoke to you several times... and glad to hear you fixed the problem but please state where you purchased your PCM/ECM...

A couple of guys (including you) have complained about past service with other companies, Soooo... give us the low down...
Who, where, contact name, how much, since you started from scratch and got a totally rebuilt one (which I like), what information do they need to program it and match it to the car... you know, give us the details!!!

As always...Thanks.
cat

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Buying a PCM Replacement
Jan 4, 2009 2:14PM PST

Hello Cat5 Cane
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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PCM Lesson learned
Jan 4, 2009 10:55PM PST

Asky...

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...

I'm Going to start a new thread titled "Jeep PCM/ECM Replacement, lesson learned"... on your behalf!

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damn jeep
Dec 19, 2008 9:24AM PST

i have a 96 grand cherokee that stalls as well so if i wiggle the conectors at pcm and it stalls then the screw trick should fix it my wife is pregnant and i dont want her to get into an accident becasue i bought her a used pos

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99 GC 4.7L stalling
Jan 5, 2009 11:07PM PST

WOW what a great forum.

I have a 1999 GC with 157K. It runs like a top.. until it gets just below 1/2 tank of gas. Then it stall like it ran out of gas. Add a gallon of gas and it's back to normal.

I replace the in-line filter but the old one was ok. I think now it's time to drop the tank and take a look...

what do you think?

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99gc 4.7 STALLING
Jan 5, 2009 11:41PM PST

IF ADDING A GALLON OF GAS GETS U UP RIGHT AWAY; MY BEST INSIGHT WUD BE THAT THE SOCK TUBE HAS DROPPED OFF THE FUEL PUMP. AS THE SOCK TUBE IS CONNECTED ON MOST OF THE JGC'S WITH A ZIP TIE....A FIALURE WIATING TO HAPPEN..... YOU SHOULD PROBABLY PUT A CLAMP THERE. PRESSURE TEST THE PUMP BEFORE YOU START, YOU SHOULD FIND THERE IS SUFFICIENT PRESSURE; BUT JUST IN CASE THERE ISN'T YOU CAN HAVE A FUEL PUMP ON HAND. BUT THE PUMP IS PROBABLY GOOD AND BE SURE TO CHECK THE CONDITION OF THE TANK ON THE INSIDE... NO BLACK RESIDUE.....IF THERE IS YOUR TANK IS BREAKING DOWN...JSUT SOMETHING TO LOOK FOR.

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1994 Grand Cherokee Stalling
Jan 18, 2009 10:41AM PST

I have a '94 Grand Cherokee with the 4.0L and I have this stalling problem. It just quits sometimes driving down the road and won't start back up. Funny thing is I found out if I bang on the bottom of the gas tank it will start right back up. I'm thinking there is a problem in the fuel pump module somewhere. Any ideas?
Thanks for any info.

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My 1997 Jeep is stalling, help!
Jan 20, 2009 3:45PM 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 Sad! 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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Jeep stalling
Jan 12, 2009 11:00AM PST

Thank you so much ! My 1998 Jeep Grand Cherokee was getting worse about stalling. A week ago, it took me an hour to go 15 miles. I was ready to blow it up. I had found your advise that morning and was planning on trying it as soon as I got home from taking my son to get his braces. Needless to say, I didn't make it home that day. Had to leave it at my daughter's work. My husband was out of town so as soon as he got back on Sunday, I let him read about this, he got his tools and we went to get it. He just backed out 1 screw on the PCM that he could get to without removing the reservoir. It cranked right up and ran like a charm all the way home. When we got home, he took the other screws out, cut them down to 1/4" and put everything back together. Today is the first day that I've drove it without it stalling in over 4 months. I just wish I'd found this information a $1000.00 ago. Thanks again!

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Backing out screws.
Jan 13, 2009 12:57AM PST

Just so you know, backing out the screws really works but the stalling might come back especially if the battery was disconnected. If it does, next thing to do is to eliminate the metal to metal contact between the 4 bolts(that's mounting the pcm to the firewall) and the pcm casing. Mine restarts right away after a stall whenever I pull the top R/H corner(driver side bolt when facing pcm)towards me. Pcm is probably getting grounded from there which I remember somebody mentioned it in this thread awhile back. His jeep stalls whenever he pushes that top driver corner bolt! So install plastic washers in between the bolt heads and the case, then wrap the upper part of the threads with electrical tape just to make sure there's no metal to metal contact. This is what I did with my '97 JGC when it was still stalling even after I r&r'd the cps, relays, ignition coil, cat converter(honeycomb messed up), backed the 2 bottom screws, etc. It's been running good and not stalled ever since 8 months ago. Hopefully my pcm did not get damaged from it. Thanks to my fellow A&P 1996JeepGC for his discovery of the pcm getting shorted or grounded. Gave us the idea of what to look for.

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Jeep Grand Cherokee Computer plug?
Jan 13, 2009 3:02AM PST

I need to replace the plug that goes into the computer on my jeep. where can i get one? or do i have to replace the whole wiring harness?
thanks for your help

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fixed my stalling proplem with a little tweak to ecm/pcm
Jan 24, 2009 10:05AM PST

I tweaked my ecm/pcm by loosing the three longer bolts that hold the unit to the firewall. then i put a roll of one inch masking tape under the bottom of the ecm/pcm so it forced the unit upward, on a angle.( you could use maybe a one inch block of wood or something simular) then i tightened it down good and it has not stalled since. this fix will take 10 minutes insted of 1000.00 dollars, give it a try. let me know. timmartini@cox.net how can i add a picture to this thread

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1996 jeep Grand Cherokee stalls when you least expect it.
Jan 28, 2009 3:57AM PST

Have 1996 Jeep Grand Cherokee 4.0 liter with stall problems for the last 4 months. Normally stalls at low rpm and at stop lights or while sitting in my driveway at idle.
Have seen a lot about screws to long on PCM.
Took off plastic cover of PCM, disconnected the three plugs.
It has three screws as you look from the front of vehicle (2 passanger side and 1 driver side, I shortened these screws, they are about 2" long) that holds the PCM to an insulating plastic plate that is then bolted to the firewall. The only screw that the PCM has are 4 corner screws that hold the cover on. Are these the screws that you are talking about. Do I need to remove the metal cover to see the other screw that are the problem?
So far I have changed the Idle air control valve (very dirty and cleaned area with throttle body cleaner, New distributor cap, New distributor rotor, Cleaned the ASD contacts, Cleaned the throttle body (very dirty), new plug wires.
The only other things that I know would cause a problem is an electrical short, Crank shaft position sensor, Cam shaft position sensor or throttle position sensor.
HELP!