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Jeep Grand Cherokee PCM Module Replacement



  • 03fxdwg03fxdwg Posts: 2
    New, new MOPAR PCM handled under warranty. Has run without a stall, stutter or back-fire for 9 days. Should have made them try that last August.
  • I have finally got back on to post. the sign in button has not workrd for me for like 3 months. Anyhow i finally found all the issues with my 93 grand cherokee. First i had a short on the power supply to my coil that was touching the frame creating alot of other problems. second i found another short between my tranny and the body coming off the main harness going to my oxy sensor-this one sucked as i had to pull the tranny just to find the short let alone fix it. luckily none of the shorts fried my pcm but every shop in town told me it was my pcm-except for the napa shop they are the ones that told me i had multiple shorts to just replace all the wiring harnesses in the jeep. instead i just rewired it my way the right way. and runs like a charm for having 230,000 miles on the engine
  • jkalvinjkalvin Posts: 2
    Can anyone possibly tell me exactly how to find and replace this sensor? I have an intermittent stalling problem. I have checked the fuel pressure and replaced the following:

    Throttle sensor
    Cam Shaft position sensor
    Distributor cap
    All wires

    The dealers have said that I should be able to R&R this sensor without removing any other parts. I can find, what I believe is an oil sensor next to the distributor. Then, behind this, close to the firewall, there is a cable, leading to a connector, which looks like the replacement part I have, but I am not positive it is the correct connector. (The replacement part has some specific markings on the outside, which are not on the part on the car. Is this important?)

    I am not able to see, nor feel the othe end of this wire to confirm that this is the correct sensor. If you have any photos or clear instructions on how to get to this part, I would greatly appreciate your help.
  • rev4revrev4rev Posts: 11
    Changed mine on a 94. I believe the dealer fibbed to you. You have to remove the oil sending unit and emission tube just behind and below the oil pressure sending unit. Then plan on some skinned knuckles working back there. That is what the repair manual said anyway and I tried doing it without removing that stuff to no avail. I even thought about boring hole in firewall and coming thru there to get to it but decided on skinned knuckles instead.
  • rev4revrev4rev Posts: 11
    Oh also the replacement one i got from the dealer was thinner and they told me to just use shorter bolts. not sure about markings.
  • jkalvinjkalvin Posts: 2
    Thank you so very much. I will give that a try. I spent hours yesterday trying it from the side of the valve cover, and earned numerous scratches and scraps and lost a 1/2" socket.
  • toledtoled Posts: 1
    The yellow light sign in the control panel stays lightened up with any of both original car keys of my cherokee classic 2001.With this light on car wont start.
    I have a friend who had same problem and in the chrysler service shop told him the PCM had to be replaced.

    Have any of you experienced same problem and solved it without replacing PCM?
    On other hand i've checked pcm sales on line andt they require the VIN number.
    What is the VIN number and where do i find it?
  • axe41axe41 Posts: 2
    I have a 1996 Jeep Grand cherokee Larardo 6 yl. It wont start but it turns over. Im getting no spark. Checked the coil and it is not getting power to the coil. Someonoe suggested changing the Power Control Module (PCM). Before I do that is there any other suggestions that my work?
  • i would check your auto shutdown relay your engine fuses and test ohms from the battery to the positive side of the wire going to your coil for shorts first but usually if there are shorts going to your coil they take the pcm out so check for those first before replacing the pcm
  • axe41axe41 Posts: 2
    thanks i will try that out and let you know how it works
  • Have you tryed a zip tie around your coil. I had a problem with mine just dieing. The wiring connector sometimes at the coil just don't get a good connection.
  • I am having trouble with my 1993 Grand Cherokee Laredo (Automatic 4.0 with 6 plugs). I purchased this vehicle out of a barn where it had been sitting for a couple of years. I was having trouble starting. I.E. would crank for up to three minutes before it would start. I have since replaced the cap and spark plug wires, spark plugs, the crank sensor on the fly wheel. (Boy was that a treat and thank god for having a mechanic for a neighbor and friend helping me!) After not being able to get it to start for a week straight, I was sitting inside the jeep thinking my next steps. I noticed the computer display panel by the Automatic shifter wsn't set. I set the the time and date, then said what the heck "I'll give it a try." The car started after hearing clicking noises from the relays. I have since then noticed that when I turn the key in the ignition, my jeep does its normal bulb checks and starts fine. Yet if the CHECK ENGINE light does not appear when it does the bulb check in the display panel, it will not start. When this light does not turn on, I do not get fuel pressure or spark to the plug.
  • hello, i have the same problem, the pcm is bad and i found one off ebay for $80 check here first and no my boyfriend is a mechanic and he took it out within minutes, the coil is not sparking either but took out coil tested fine but put coil back in tested bad so thats why he said its the pcm hope this helps a little i ordered my 1993 jeep grand pcm but thought you could get any if it comes out of any 1993 jeep grand but boyfriend says i hope its the right one so tomorrow i gues we will find out so if you shop make sure its compatible or the same numbers my numbers we all the same except for the last two not sure if it makes a difference or not til tomorrow.michelle
  • i have a 1993 jeep grand cherokee wagon w/ 5.2L v-8. security light stays on, climate control display just says error and is non responsive. anyone have any ideas? i can answer any questions about the jeep if you need :)
  • be sure that you get the pcm that has a security or non security on it. There are TWO (2) types..If you need one I have one here that I will never use because after much bs from the dealer it just turned out to be the coil...just to be safe replace it not just have it tested..its only 20 bucks at a auto parts store..cheep!
  • New to the site. I have a 1994 Jeep Grand Cherokee Laredo 6Cyl/ 4x4. I suspect the PCM but the following has puzzled me. The car starts and runs for 12 minutes and abruptly dies. Restart attempt(s) shows no spark. Strong cranking power, relays energize - but nothing. Three days later the same pattern - starts- runs for 12 minutes- dies and then I must once again wait three more days to hear it run again!! (in those 12 mins it sounds dynamite!)

    Car has new fuel pump/ gas tank/ battery/alternator (replaced over time with none of these items over two years old). car has had regular tune ups and oil replaced at every 5K

    I think the PCM at fault but I am not to experienced with the many sensors the car has on-board. I wonder if a faulty sensor could be triggering the shut down and hope to lean on someone with more experience before dumping $300.00 on a new PCM

    Any help or direction would be MOST appreciated. Thanks in advance for any possible suggestions to resolve my issue.
  • hi, i have a 93 jeep and i replaced my pcm for $80 off ebay motors go there first, it ran great for 2 weeks and then had to replace throttle position sensor at advanced auto for $35 with warranty now the jeep has a temperature problem with starting at certain times so my mechanic says try putting in new spark plugs becuz the older jeeps need certain spark plugs and he thinks the wrong spark plugs are in the jeep now go platinum not the cheapy ones either.hope this helps,having problems too.
  • also found pcm on ebay for you but this is the guy i bought mine off of and i wealed dealed with him he wanted 95 plus shipping so i offered him 80 with him paying for shipping. and he did here is the website to go to,

  • hello again, i just got an email from ebay member and he wants to know what your pcm number is, he does have one for you 1994 but wants to know what the numbers are and see if they are compatible here is the ebay guys email

    eBay Member: oldtowman"

    the other webisite i listed for you is the one i actually bought mine from so here is either one that has a 1994 pcm good luck
  • Thank you so very much for this information. I will obtain the info and be in touch with him. Thanks again!
  • I have a 2001 JGC it...hit animal and punctured radiator...thank god for comp insurance. Replaced radiator...drove for 20 miles...overheated...fluid pouring out of the bottom. Towed back to the service place...coolant everywhere under the hood. Impellor broke on water pump...coolant backed up in overflow and then sprayed out hose for overflow...replaced everything on the cooling system....driving home stalled out....had electrical power to everything.....pulled over...tried to restart....acted as if it was flooded. sat for a few minutes...started up.....Drove another 20 miiles....same thing...tach to zero....had electrical power.....restarted right away....while driving again it jerked and a few minutes later...stalled out. Had got gas and thought it was bad gas....filled tank and added dry gas.....droveit all the way home...stalled pulling in driveway. It acts as if it is not getting enough gas.....any thoughts?
  • I am not a mechanic but this sounds like a PCM. My other Jeep had the same issues - replaced gas tank / fuel pump (obviously fuel filter and spark oplugs were also replaced) and the stalling out issue wasnt resolved until the PCM was replaced. Good luck
  • tuggajbtuggajb Posts: 646
    the computer sits right by the overflow tank on this jeep has a big bundle of cables hooked to the computer with bolt in the center of plug in

    unhook the battery and remove the plug of wires use clectric cleaner to clean contacts put dilectric greese on contacts put back together should work

    think you got antifreeze mix inside conector
  • well, replaced the pcm like i said then replaced the throttle position sensor and cleaned throttle body which wasnt that dirty, but that darn jeep only wants to start at certain times,its weird it will start sometimes in the heat but when it gets cold it wont but then other times it starts when its cold out havent replaced spark plugs yet thats the next thing, any thoughts on maybe the fuel pump?i was really trying to avoid the fuel pump replacement idea but might have to.
  • neguyneguy Posts: 1
    have you figured out anything yet? i will keep reading more post and see if you found anything but i saw this first and said that sounds like me. my next thing is gonna be the camshaft position sensor.
  • Hey,

    I'm new here and am hoping to get some input to resolve my problem. My inline 6 started misfiring at 35 mph and the check engine light starts blinking on and off. I had the codes checked and all that was indicated was cylinders 1, 3 and 6 were misfiring. Upon resetting the light, the problem went away. Next time I drove it, the misfiring and blinking light came back. Any ideas or similar experiences?

  • i have a 93 5.2 grand cherokee that will not start i replaced coil,crank sensor, cam sensor, had pcm rebuild, no spark at the coil or wires used 2 differnt coils to see if any change bu nothing i had problems with the pcm befor it stoped only about 10 or 15 min running time then you let it site for about 10 min it well restart last week it started to do it all over again and died on the fwy so i checked crank sensor and cam sensor and replaced but still nothing can any body tell me what to do i had a mechanic look at it and he says he think it is the pcm even if i had it rebuild
  • I'm not a mechanic but I would agree with his assessment. I had a rebuilt PCM that also needed replacement. Good luck
  • Hello everyone again. Well after much to do with my 93 jgc my son wanted to get his own but of course do me one better so he got the 5.9 jgc. Great Jeep until a few days ago. He went 4x4ing with it and it started to sputter then died. At first I thought "this will be easy, just some water in the dist". Well he got it home and I found no spark from the coil to the dist. Well easy replace the coil? Ya right, did that and still no spark. Well after going thru all this with my 93 the first thought is the camshaft ps. Replaced that and still no spark out of the coil. PCM..easy my sister has a 5.9 also and stole the PCM out of it and still no spark..I know what your thinking maybe mine was bad. I put it in her Jeep and it ran fine. Darn it I thought, lets try all the relays so one by one I took them off her jeep and replaced it with the one from my sons Jeep. Nothing again I have no spark.

    So after all this I am at a loss here. Can anyone give me another idea on where to go from here? Again I have a running 5.9 to swap parts from and to check my parts with to be sure if its working...So please anyone have somewhere to go?

    The only other thing I was thinking was a crankshaft ps..but is that any different from the camshaft ps? If so where is it located?

    Thanks so much in advance,
    Jeff...and son.
  • cthessingcthessing Posts: 1
    Guidance needed - My 2005 Jeep Grand Cherokee Limited 5.7L V8Hemi is beginning to seem possessed. Either during driving or upon starting, the entire electrical systems blinks a time or two and then completely shuts down. I can strill drive but no guages, air conditioning or lights (inside or out). Could this be an easy fix with a new powertrain control module? Any thoughts?

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