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Unread 06-12-2013, 10:46 AM   #1
jlconlin
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Difficult to Replace Computer?

I've been told that the "computer" needs to be replaced on my 1997 Grand Cherokee. I can replace most parts in my Jeep if someone will just tell me what needs to be replaced.

Is the computer easy to replace in the 97 Grand Cherokee? I really don't want to pay someone $500+ to replace it if it is easy enough and I can get the part for about $200.

Thanks,
Jeremy

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Unread 06-12-2013, 10:49 AM   #2
RnEmOvr
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Disconnect battery, undo 4 bolts and unplug then reverse for install
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Unread 06-12-2013, 10:49 AM   #3
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http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40

If I recall correctly still need to get it flashed by a dealership.
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Unread 06-12-2013, 10:59 AM   #4
jlconlin
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Quote:
Originally Posted by RnEmOvr View Post
Disconnect battery, undo 4 bolts and unplug then reverse for install
Doesn't sound too bad. Maybe I'll get my 9-yr old son to help me out.

The parts I've seen at Autozone and OReilly websites don't mention that they need to be programmed "zapped" after installation. (Some of them do, but most do not.) Does anyone have experience with this?
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Unread 06-12-2013, 11:00 AM   #5
jlconlin
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Quote:
Originally Posted by DNFJ View Post

If I recall correctly still need to get it flashed by a dealership.
I've seen several parts online that don't need to be programmed or flashed. Is this believable?
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Unread 06-12-2013, 11:07 AM   #6
dellis
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Yes, it has to be programmed for your car ... otherwise, it is just a piece of hardware without software. Costs about $80 for the software installation.

Some of the on-line retailers (on eBay for example) will do the programming for you.

Make sure you buy a "re-manufactured" unit, and not one that has been spit-polished.
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Unread 06-12-2013, 11:56 AM   #7
Oldfrog
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The 97 model does NOT need to be flashed. I have a 97 and have replaced the PCM ( more than once).

How do you know that you need a new PCM ?
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Unread 06-12-2013, 11:58 AM   #8
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careful buying used PCMs, they are known to go bad after sitting disconnected from the vehicle
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Unread 06-12-2013, 01:03 PM   #9
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I have a 94 regular pcm. Who wants it?
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Unread 06-12-2013, 01:50 PM   #10
jlconlin
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Quote:
Originally Posted by Oldfrog View Post
The 97 model does NOT need to be flashed. I have a 97 and have replaced the PCM ( more than once).

How do you know that you need a new PCM ?
I took it to a mechanic who drove my Jeep around and couldn't replicate my problem. Then, when he wiggled the PCM, the Jeep immediately killed. It makes sense that the PCM needs to be replaced. Is that too premature a diagnosis?

(My original problem was that my Jeep didn't run well. It backfired, stuttered, sometimes died while running, and had difficulty starting.)
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Unread 06-12-2013, 02:28 PM   #11
OverlandZJ
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Quote:
Originally Posted by jlconlin View Post
I took it to a mechanic who drove my Jeep around and couldn't replicate my problem. Then, when he wiggled the PCM, the Jeep immediately killed. It makes sense that the PCM needs to be replaced. Is that too premature a diagnosis?

(My original problem was that my Jeep didn't run well. It backfired, stuttered, sometimes died while running, and had difficulty starting.)

Common issue.. the problem is the contacts from ECU to harness. Lots of guys have disconnected, cleaned and reassembled. Use a few zip ties if necessary.

Do some searching here... several threads covering it.
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Unread 06-12-2013, 03:07 PM   #12
MyKeyB
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^^^
I'd try this first:
http://www.jeepforum.com/forum/f13/i...l-fix-1487443/
It's nothing else, it's free.
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Unread 06-12-2013, 03:24 PM   #13
jlconlin
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Thanks for those comments. I'll see if I can clean up the contacts and other simple maintenance and save me a few hundred bucks.
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Unread 06-12-2013, 10:29 PM   #14
shackwrrr
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The only thing that need programmed on a new ECU is the vin, Everything else will function as designed and run fine if no other issues are present. The only thing that will happen is the check engine light will be on with a code P0630 which just means VIN mismatch or not programmed.

Oldfrog, do you have a security system factory? Im asking because if you use a used PCM with some kind of vin in it no codes will set if there are no other modules in the system that have the vin in them.
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Unread 06-13-2013, 12:50 AM   #15
Oldfrog
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No factory alarm on mine. I have only bought refurbed PCMs, never any "used" PCMs....like from Ebay or a JY, etc. ( I know they are all technically "used" because they no longer make new ones. You get my point, I'm sure)

The 97 pcm doesnt need any programming. Never has the question of a factory alarm even arisen when I bought them....not from Cardone, anyway. My guess is that the BCM or some other system is storing that info. Zeejay will know the answer to that one.

To the orginal poster, I suggest he remove Negative battery cable, then the PCM connectors, spray the heck out of them with electrical contact cleaner, let them dry, apply a TINY bit of dielectric grease to the female side of the connector at the pin holes, carefully reinsert them, make sure they are locked down and then zip tie each one. Only if the ZJ makes it 200+ miles without a stall or near stall, will he know if that's the issue. 400 is better.

But if he has some other issue that has caused the stalling ( see Zeejay's list and "work" it...) it may well have messed up the PCM. Plus, they ARE known for having poor solder joints inside. Do NOT, I repeat....do NOT buy a PCM from either of those outfits in Florida. Yes, they are on ebay too. Don't say I didnt warn you. If you are certain you need one, go to Oreilly's,etc. and get a Cardone brand. Keep the receipt, for the warranty because it's hit or miss with some of these PCMs. Or you could get one from Kolak, here on the forums.
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Cajun Recipes and Fishing tips

Words of wisdom, Posted by Zeejay:
"..it's not air, it is the opposite of air... suckage so to speak."

Stalling? Work through Zeejay's list
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