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Unread 10-24-2006, 08:45 PM   #16
Scafone
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Those pics are very helpful. Thanks.

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"Laws that forbid the carrying of arms...disarm only those who are neither inclined nor determined to commit crimes...Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man."
--Thomas Jefferson
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Unread 10-24-2006, 09:13 PM   #17
John in MA
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Keep in mind that those pics are of a personal computer motherboard. Unless your ZJ plays Quake it's not an exact match.

Here are a few photos of my old PCM. Again, just remember that these may not be your problem. It's likely, but you never know.






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Unread 10-25-2006, 06:53 AM   #18
Scafone
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Those pics help even more.

Do you guys know of a good place to find another ECU? I'm hesitant to buy used, but a quick ebay search came up with used ones ranging from $129-149.

$279 to refurbish mine at ECU Direct
$35-250 junkyard prices
$680 from the dealer!
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"Laws that forbid the carrying of arms...disarm only those who are neither inclined nor determined to commit crimes...Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man."
--Thomas Jefferson

Last edited by Scafone; 10-25-2006 at 12:13 PM..
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Unread 10-25-2006, 07:11 AM   #19
greasefingers
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Those are great pics Joe! Thanks for sharing that.
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Unread 10-30-2006, 07:37 PM   #20
Scafone
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Update

I'm now even more sure that my original problem lies with those capacitors. I just tried out my junkyard ECU. It has a different part #, but is supposed to work as well according to the junkyard and my local dealer. With this ECU, the fuel pump primes right away as it should, but will not start. As soon as it fires, it then dies. I guess I'll call the dealer about having this new one "flashed", since I was told this might be necessary.
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"Laws that forbid the carrying of arms...disarm only those who are neither inclined nor determined to commit crimes...Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man."
--Thomas Jefferson
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Unread 10-30-2006, 07:40 PM   #21
greasefingers
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If the PCM from the junker came out of a Jeep with a security system, then it will start and then die after a few seconds; if the original PCM did not have this feature.
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94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
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Unread 10-30-2006, 07:54 PM   #22
Scafone
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Quote:
Originally Posted by greasefingers
If the PCM from the junker came out of a Jeep with a security system, then it will start and then die after a few seconds
It doesn't start, but almost. Can a security system computer work in a non-security system Jeep?

The computers look differently as well. In addition to the plastic case having screws to open, the junkyard ECU also has this big finned deal. My original is like the ECU Joe posted.

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"Laws that forbid the carrying of arms...disarm only those who are neither inclined nor determined to commit crimes...Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man."
--Thomas Jefferson
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Unread 10-30-2006, 08:44 PM   #23
jeep946
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the large fins are from an older stile computer. it has sense been updated. does your old computer have a big black bold number on top. like 300 or 289. let me know. i can hook you up with the right computer. i am the guy that sold john his new computer. it took some time to get to him but i have sense fixed that problem, sorry john. the light is great. i got the larger bulb and batt. made a big big change, thanks aging
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Unread 10-30-2006, 10:28 PM   #24
John in MA
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The photos I posted are from my original early '94 "300" suffix computer, but the late '94 (comes up as a '95 online) "026" that Jeep946 sold me is identical in every way. Other than the writing on top there's no difference whatsoever. Beyond those models I'm not sure what came with what, especially the V8 ZJs (mine's an I6). From what I've read the capacitors are the same, just in slightly different locations.

As far as I know, pre-96 ZJ computers don't need to be flashed to function. They're more basic than the later ones. I'm also inclined to say it doesn't sound like a security system issue, but I've never fussed with one of those.

What're the complete model numbers of both your old and new PCMs? I have a few Mopar dealer parts lists with various numbers.
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Unread 10-31-2006, 05:47 AM   #25
Scafone
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My original is: 56029302, dated 10/23/93
Junkyard ECU: 56028112, dated 10/20/93

The junkyard and my local dealer said that one other computer would interchange with my -9302 computer, and that is pn: 5628113
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"Laws that forbid the carrying of arms...disarm only those who are neither inclined nor determined to commit crimes...Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man."
--Thomas Jefferson
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Unread 10-31-2006, 06:33 AM   #26
greasefingers
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Quote:
Originally Posted by Scafone
Can a security system computer work in a non-security system Jeep?
No it can not
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94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
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Unread 10-31-2006, 10:31 AM   #27
John in MA
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Those all come up as non-security numbers. It should work, assuming the computer is functioning properly.

My ZJ's original -300 PCM is listed online as for both standard and anti-theft systems--my truck's a standard. The replacement is listed as for standard.
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Unread 10-31-2006, 10:58 AM   #28
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Great thread! Wondering what the four adjustments do.

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Unread 10-31-2006, 11:18 AM   #29
Scafone
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Those aren't adjustments...they are impressed into the gel-type stuff during the manufacturing. I can't tell you what they mean, but they're found on many plastic automotive parts.
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"Laws that forbid the carrying of arms...disarm only those who are neither inclined nor determined to commit crimes...Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man."
--Thomas Jefferson
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Unread 10-31-2006, 11:27 AM   #30
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Quote:
Originally Posted by Scafone
Those aren't adjustments...they are impressed into the gel-type stuff during the manufacturing. I can't tell you what they mean, but they're found on many plastic automotive parts.
Dang, was thinking I could pick up a few HP cheap.
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