97 grand cherokee 4.0 no start - JeepForum.com
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post #1 of 45 Old 05-31-2014, 11:40 AM Thread Starter
Izzybird
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97 grand cherokee 4.0 no start

Hey guys, I'm about to pull what little hair I have left out dealing with this thing. Picked it up for $500 with the infamous stalling problem, jeep is very clean and nice for its age. Tried all the fun tricks and fixes on the pcm and of course the problem always came back. Took out the pcm and took it to my buddies business and stuck it in his transmissive real-time x-ray, really cool expensive machine I must say. We saw nothing wrong with it so he cracked it open and poked and prodded, said everything looked good and found no cracked solder joints or anything out of the ordinary. Stuck it back in and now I do not have 12v going to the coil. I've searched relentlessly and performed many tests with a multimeter, coil ohms good, asd connectors seem to check out, fuel pressure to the rail, good grounds, new oem crank sensor, and on and on. I am very open to suggestions, I'm a hobbyist and not a mechanic by trade. Was going to go grab a cam sensor and toss it in but town is 30 miles away so I will wait until I need to make a beer run . I did get a o2 sensor code once, unplugged the downstream and didn't seem to make any difference. I realize the only thing I've changed is opening up the pcm so logic would dictate that would be the problem, but it seems other things would be afoul if the pcm was dead. I'm close to giving up on it and adding it to my bone yard, it's really too nice of a vehicle to do such a thing.
Thanks all,
Izzy

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post #2 of 45 Old 05-31-2014, 12:16 PM
Oldfrog
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Unplug the upstream o2 sensor....disconnect the battery for a few minutes and try again.

BTW, you cant always see a cold solder joint. Most experienced electronic techs can, but not always.

Go thru the dirty dozen, step by step.
http://www.jeepforum.com/forum/f13/1.../#post14045654

2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.
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post #3 of 45 Old 05-31-2014, 12:52 PM Thread Starter
Izzybird
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No dice, I just realized I'm getting no tach movement while cranking also.
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post #4 of 45 Old 05-31-2014, 08:03 PM Thread Starter
Izzybird
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I've been through the dirty dozen pretty thoroughly, I'll pick up a cam sensor from the dealer Monday and then see if I can find a known working pcm to swap in. I hate to part this little fella out, but I've about had it.
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post #5 of 45 Old 05-31-2014, 08:24 PM Thread Starter
Izzybird
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Hmm, now that I think back.. When I first got this dodge with a jeep emblem on it the little screen right in front of the shifter started smoking and tried to catch the dang thing on fire. Not sure what it even does since it didn't work when I got it. The infamous stalling slowly started right after that. May be just coincidence. I called the lady I bought it from and she said it never stalled on her the whole time she owned it since new. Said she sold it to me cheap because of the growling moan the rear end was making. On a side note, I threw another rear end under it with a Detroit no-slip I had already. Little sucker is a tire eating maniac now, bit it would chug through some rough terrain for a 2 wheel drive.
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post #6 of 45 Old 05-31-2014, 08:39 PM
Oldfrog
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Hmm....the VIC was smoking?

I am assuming you have checked fuse #20 under the hood, correct? If it's blown, check the lower o2 sensor wiring....a known problem area.

2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.
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post #7 of 45 Old 05-31-2014, 09:31 PM Thread Starter
Izzybird
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Yes, all fuses in cab and under hood are good. I shut the key off and yanked the battery cable off for good measure, it was burnt all around one of the heat sinks if I remember correctly.
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post #8 of 45 Old 06-01-2014, 04:10 PM
dusterdude
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Have you put a new crank sensor in it?
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post #9 of 45 Old 06-06-2014, 11:52 AM Thread Starter
Izzybird
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Yes, oem. Dealer wants $93 for a dang cam sensor, ridiculous. I think I'm just going to let it have some quiet time in the bone yard. I may part it out or I might decide to work on it some more on down the road. We'll see. I've got bigger fish to fry for now. If I get it running, I'll post up what I did for future readers.
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post #10 of 45 Old 06-06-2014, 12:44 PM
ZeeJay1997
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i think the moral of this story is to never stick your pcm in a really cool expensive xray machine
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post #11 of 45 Old 06-07-2014, 10:27 AM Thread Starter
Izzybird
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You may be on to something there! I have a sneaky suspicion that when I get a known working pcm she's gonna come back to life. You'd think it would at least spit and sputter some when trying to start it if the pcm is bad. But hey, what the heck do I know!?
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post #12 of 45 Old 07-11-2014, 07:52 PM Thread Starter
Izzybird
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Well, I'm back. Located a pcm in a wrecked 97. I wasn't there but they said they fired up the motor to make sure it ran, pulled the pcm, and I brought it home. It did say reman on it unfortunately. Threw it in the jeep and fired right up!... Died 2 seconds later. Every single time, fires right up and dies almost exactly in 2 seconds. When it dies I can cycle the key before the motor stops turning and it runs another 2 seconds. Keep cycling and it will basically stay running. Guess it at least told me my old pcm was shot, apparently this one is crap too. I need to find someone close who has a grand cherokee 4.0 to throw this pcm in and see if it does the same thing. What a bummer.
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post #13 of 45 Old 07-11-2014, 08:05 PM
ZeeJay1997
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the PCM engine no run feature is enabled by the security system of the donor vehicle.

do you have the key fob and does the security system work?
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post #14 of 45 Old 07-11-2014, 09:33 PM Thread Starter
Izzybird
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Yes, I do have the key fob to my vehicle. I do not know if the security system works/worked on my vehicle, never tried it. My key fob has lock, unlock, and panic buttons on it.
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post #15 of 45 Old 07-11-2014, 09:34 PM Thread Starter
Izzybird
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Or are you asking if I have the key fob from the donor vehicle?
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