Question about 1994 Jeep Grand Cherokee

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Ive tried to replace my pcm in my 94 jeep grand cherokee with used ones from a junkyard. I made sure part # was exact and made sure vehicles they came from did not have security systems. All three times I tried different pcm's it would fire right up and die. What am I doing wrong? Ive read other forums that said they went to a junkyard and matched the part # and it worked great for them.

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  • Jason Reed
    Jason Reed Nov 21, 2013

    Thanks. My jeep runs with the origanal computer but It misfires bad until you warm it up and drive it a while. Thats why I was trying to swap the computer in it. Im curious why It wont run with any of the used computers Ive tried even with the same part # and no security?

  • montehammons Nov 21, 2013

    I see. Good question-I don't know, but it may be that your original computer might be doing the same thing now??? Or have you put it back in? Sounds like you may have a sticking valve or lifter problem-I would try a compression test to see if you could find a problem that way. Try to determine if the misfire is isolated to a single cylinder, or if it's all over the engine. A single cylinder could be an injector problem, possibly ignition, and possibly mechanical.

  • Jason Reed
    Jason Reed Nov 21, 2013

    yes I put the original comp back in. starts right up. idles fine but misfires bad if you accelerate to 2000 rpm or above. If you put it in reverse you can barely get it to move or it will die.The more it warms up the better it gets. the more you drive it the better it gets. Just left it at the dealership for a week and they have no answer without tearing into guesses that will cost money.

  • Jason Reed
    Jason Reed Nov 21, 2013

    No one can make sense of the fact that its so much worse in reverse than in drive. But if you were to drive it for 30 miles you would never know it had an issue.reverse works perfect ,fuel mileage goes back up to at least 14. It shows around 8 or 9 mpg if not fully warmed.

  • Jason Reed
    Jason Reed Nov 21, 2013

    Your right though I need to figure out if its certain cylinders misfiring. Passed compression test, fuel pressure test. been on a scanner numerous times, doesnt throw a code. I keep hoping its a loose connection in a plug or wire harness. Its getting frustrating

  • Oliver Henderson
    Oliver Henderson Dec 06, 2013

    PCM grounding out? Reverse "pulls" it in the opposite direction....Back the screws off?

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  • Jeep Master
  • 5,252 Answers

3 times, same symptoms-must be something else. Check crank position sensor and cam position sensor. Crank sensor is for ignition timing-advance and retard. Cam sensor is for fuel injector synchronization. If one is bad, it may cause problems like yours. Just a suggestion.

Posted on Nov 20, 2013

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Posted on Jan 02, 2017

  • 1 Answer

SOURCE: 1994 Jeep Grand Cheroke engine dies every few miles

This is 100% certainly the "CKP" or crank possition sesor. I had the same problem on my SE 4.0L cherokee, i replaced the ignition pack - leads, dizzy cap, coil as the dizzy cap had major dirt and arc marks inside, king pin lead was loosing connection when warm also.
However this did not solve my problem, it helped, thats it.

I then used the in car diognostic system to see what that told me, sure enough - code 11, code 12 and code 55. meanings as follows.

11- no signal from crankshaft sensor
12 - main battery power disconnected
55- end of test

Once i replaced the crank shaft sensor and disconnected the battery for 30 mins to reset all fault codes it removed code 11.

Follw this link to learn how to use the on board diognostics - http://members.cox.net/wilsond/engine_codes.html

Hope this helps people out there!

Joe

Posted on Feb 23, 2009

  • 45 Answers

SOURCE: 94 Jeep Grand Cherokee Transmission Problom

1994 is the same as 1997. parts are interchangeable

Posted on Dec 31, 2008

  • 40 Answers

SOURCE: My 02 Jeep runs great but oil pressure reads High all the time

oil pressure sending unit is not working right.

Posted on Mar 08, 2009

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1 Answer

How to remove a dashboard from a 1994 grand cherokee


XJ 94
its not bad, wana bet? 90% are not.
(i used to fix them)
so the PCM,. the FSM book covers that.
why not read that.
JEEPJX
PCM is baD ONLY WHEN inputs good, and its outputs are bad.
(and outputs not shorted) !!!
(same or all computers on earth)
lose of power to PCM or ground
or bad power.(weak, or intermittent)


Got DTC errors , post them?
innova 3140 best bank for buck on 93-95 jeeps. !!!
that is a low priced scan tool

are you having ASD relay issues?
http://www.fixkick.com/Jeeps/ASD.html


see XJ 95 here (same i think)
http://colorado4wheel.com/manuals/Jeep/XJ/

page 8D-23
engine bay next to Air cleaner.

to diagnose any car, a real scan tool is best.
or you will need a full lab of meters and scopes. like me.
the scan tool show up things the keyon/off trick does not.
http://www.fixkick.com/Jeeps/jeeps.html#poor_mans-scan


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Mar 01, 2015 | 1994 Jeep Grand Cherokee

1 Answer

Ive got a 94 jeep grand cherokee 4.0 liter i put a 93 4.0 liter and caint get it to fire but it has different distributor


i think you pretty much answered your own question there. Use the '94 distributor in the other engine and make sure that all the sensors are in place, connected and all for a 94. Also check the crank position sensor. If left in place during install, they can get damaged if the flywheel hits it. (hope you matched the flywheels too...if different, it will not run.

Nov 30, 2010 | 1994 Jeep Grand Cherokee

1 Answer

Where is the DLC on the 94 loredo grand cherokee?


there are a few DCL's on this vehicle
I am assuming you wanted the DCL for the PCM
it should be under the hood near the bulkhead

hope this helps!

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Apr 02, 2010 | 1994 Jeep Grand Cherokee

1 Answer

I need to find a parts guide for jeep


for information on parts, troubleshooting and resolution of issues:
1998 Jeep Grand Cherokee Service Manual
http://rapidshare.com/files/138412864/ServiceManual.Jeep.Grand.Cherokee.1998_by_Parasico.rar

(extract using something like WinRar and retain file/folder structure; requires Adobe Reader to view the PDF files)

see also www.rockauto.com for parts and pricing
no harm in going to dearlership either for exact part numbers and pricing

i recommend going to junkyard to obtain genuine ZJ parts

Feb 05, 2010 | 1998 Jeep Grand Cherokee

2 Answers

How do i reset my pcm on my jeep grand cherokee?


try disconnecting the NEGATIVE cable on the battery for 10-20 minutes. re-connect it. start the vehicle and drive it for a few miles to let the pcm reset. (make sure the key is off and out, just to make sure you don't fry something when you remove the negative-black wire cable!!). don't short it against the positive-red!
make sure the negative connector (on the cable) is isolated from the frame, or it will still be grounded! wrap some plastic around it, or something!
good luck!

Sep 22, 2009 | 1994 Jeep Grand Cherokee

2 Answers

I have a 94 cherokee limited 5.2 v8. which transmissions are come


The 46rh is a hydraulic transmission as where the 46re is an electric transmission. With minor wiring you can replace the 46re with the 46rh but not the other way around. Your transmission would stay in limp mode and wouldn't shift out of 2nd gear. So the answer is no.

Aug 23, 2009 | 1994 Jeep Grand Cherokee

1 Answer

94 Jeep Grand Cherokee heater coil has been replaced wont start


If you have a security system, close all the doors and then lock the drivers door with the key, then unlock it. That should re-set the system. I've had the computer completely disconnected from mine several times (used it to check another vehicle) and I don't have security...it started and ran fine...only difference between the two is the security so I'd try that.

May 24, 2009 | 1994 Jeep Grand Cherokee

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