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Unread 11-09-2008, 03:22 PM   #16
fixxit413
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1992 YJ Wrangler 
 
Join Date: Nov 2008
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great info thanx a bunch-i just picked up my new ecu- can I just plug it in and start her up or is there a particular procedure to go through?

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Unread 11-09-2008, 03:59 PM   #17
sentinal02
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Quote:
Originally Posted by fixxit413 View Post
great info thanx a bunch-i just picked up my new ecu- can I just plug it in and start her up or is there a particular procedure to go through?
should be plug and play. i'd say you might want to clear any codes on the new one, but just the act of being disconnected from the harness to make the swap should do that for you.
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Unread 11-17-2008, 10:47 AM   #18
ChiroSean
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1994 YJ Wrangler 
 
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Many thanks to Sentinal02. This thread made it very easy for me (a novice) to test everything and determine the computer was bad. I am going to take it out tonight and send it out to get it repaired. But thanks again for the very detailed diagnostic writeup!
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Unread 11-23-2008, 05:38 PM   #19
ptrain
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Does anybody have any suggestions for places to get the computer repaired? It looks like that's my problem as well.
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Unread 12-16-2008, 07:53 PM   #20
greenerob
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Originally Posted by ptrain View Post
Does anybody have any suggestions for places to get the computer repaired? It looks like that's my problem as well.
Same here!! Does anyone know of places to get it repaired? What do I tell them I went done?
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Unread 12-16-2008, 08:01 PM   #21
Richmond88yj
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Do it yourself.

Honestly. it costs 6 bucks.

It takes about 15 minutes to pull it out and put it on a bench (3 bolts).

Then 6 screws hold the cover on. Remove that.

Inside is the motherboard about 6"x9". it is covered on both siddes by an inch of hardened RTV.

From the pics in the thread, locate the 3 capacitors (easy to do, they'r ethe only 3 round things sticking up through the RTV).

Then GENTLY, with an exacto knife and your finger, peel away the RTV 1/2" on all sides of each of the 3 capacitors. (1 side is the edge so that's easy)

Do this on both sides of the board.

Now take a $2 soldering iron from radio shack and heat up the underside of the capacitor connection. It;ll pull right out.

Insert new capacitor in same holes. Heat up underside again to re-melt the solder and let cool. It's now re-fused.

Repeat for cap's 2&3.

Put motherboard back in, and glob up the caps with RTV filling in the area you removed.

Put cover on and re-install.

turn key..

VAROoooooooM!

See I told ya. $6 bucks.

Take the $194 bucks you just saved, buy a lifetime JF membership and spend $94 bucks on beer!

Last edited by Richmond88yj; 12-16-2008 at 08:23 PM..
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Unread 01-19-2009, 05:37 PM   #22
snaustin09
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I have read a lot of things about replacing the capacitors for the ECU, is there anyone on here that has successfully completed this with the 4.0L? I have the same symptoms, and am hoping that this will fix it. Thanks!
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Unread 04-13-2009, 06:19 PM   #23
2ndwrangler13
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Great repair

The trouble shooting you provided was right on. After installing the 3 capacitors and encasing them back in the encapsulant the jeep turned right over. Thanks
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Unread 04-19-2009, 10:07 PM   #24
ltjblalo
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I just went through the tests and found that I'm getting about 5V across the "Dome" fuse terminals. I'm getting fuel to the fuel rail, but I'm not getting any spark. When I turn my key to ON, the CEL never comes on (confirmed bulb works). Could this be the ignition switch like you said, and it is getting enough power to prime the fuel pump, but not enough to give spark? I'm going to test the ignition switch wires tomorrow, but it is too late tonight.

Thanks!
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Unread 09-06-2009, 09:05 PM   #25
Cts6867
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Thank You

Another Huge THANK YOU for this thread. I have a 95 2.5L 5 speed and it died the other night. It would start occasionaly for about 15 sec then die and not restart. I checked the fuel, did a complete tune up (knowing it MUST be the cap or button). No good. Then I found this thread and determined that the CEL was not coming on so I hoped it was the ECM. After a $6 trip to Radio Shack and about an hour replacing the caps, the CEL came on and she started right up time after time.
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Unread 09-08-2009, 09:29 AM   #26
wifesyj
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any luck with the 4.0?

I am also wondering about this working on the 4.0. I tried replacing the capacitors, and my symptoms remain. I'm afraid I have missed a step, or was hoping this would be a cure-all, and of course, that's not the case. I have a 91 with the 4.0. very slow to start, temperature doesn't matter, CEL works. I was thinking of the CPS as being the culprit, but hate to "replace parts till its fixed". I would rather know why it's happening so we can help others with this problem.
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Unread 09-08-2009, 09:41 AM   #27
idaholtby
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If your CEL lamp comes on when the ignition is first switched on, then the capacitors in the ecm are not your problem. Yes, this covers the 4.0Ls as well, the ecm caps and related symptoms are the same between the 2.5L and 4.0L. Check for codes, if the cps is at fault, it should throw a code. If no codes, check your fuel pressure at the rail. Start a new post with your symptoms and what has been done to date so others can help you figure out what is wrong.
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Unread 09-21-2009, 11:00 AM   #28
3rdtime
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Thanks for the tip

Hey, I'm a first time visitor to this forum and hit a grand slam on the first try. My '94 Wrangler wouldn't start. I followed this diagnostic proceedure to the letter and low and behold my computer was bad. Since I have some electronic background I decided to try to repair it. It was the best $4.14 I ever spent at Radio Shack. One question I have is, how critical is the "jelly" that encases the internals of the computer? Is it for shock absorbtion or waterproofing or what? I scraped a lot of it off of the top side of the circuit board looking for screws that would be holding the board in the case only to find there were none. A gentle pull with a springhook under the edge of the board and it popped right out. Anyway, I just put some RTV around the base of each capacitor to help support them and put it back together. Fired right up. AWESOME!!!!! Thanks again
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Unread 11-11-2009, 10:56 AM   #29
TaraCrazyHair
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Will this testing work for the 94 Grand Cherokee as well?

I have the same issues regarding the CEL
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Unread 11-11-2009, 01:35 PM   #30
idaholtby
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Quote:
Originally Posted by TaraCrazyHair View Post
Will this testing work for the 94 Grand Cherokee as well?

I have the same issues regarding the CEL
If it has the 4.0L, then definatley yes. Your profile states that you have a 6.0L?
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