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Unread 04-13-2010, 10:08 PM   #1
jasman
Registered User
1995 YJ Wrangler 
 
Join Date: Apr 2010
Location: florida
Posts: 3
Jeep Engine Swap

I am new to the site and new to owning a jeep. I have a 95 jeep YJ that I purchased about9 months ago. The jeep has a 2.5L motor on a 5 speed manual transmission and 33 X 12.5 tires. Naturally, I can't even keep up with traffic on I-95. I purchased a 99 4.3L Chevy vortec and matching 4L60e transmission with 22,000 miles on it. I am 80% complete with the install in the jeep and have saved the best for last. I am not mutch of a mechanic so be patient. I need help / ideas with the wiring harness and computer. My brother-in-law is a mechanic and helped me up to now. Would like to perform the conversion without purchasing a $700 adapter harness but I will if need be. Any thoughts would be greatly appreciated.

James

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Unread 04-13-2010, 10:21 PM   #2
Bastidjeep
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2004 TJ Wrangler 
 
Join Date: Jan 2010
Location: Marion,TX
Posts: 87
Quote:
Originally Posted by jasman View Post
I am new to the site and new to owning a jeep. I have a 95 jeep YJ that I purchased about9 months ago. The jeep has a 2.5L motor on a 5 speed manual transmission and 33 X 12.5 tires. Naturally, I can't even keep up with traffic on I-95. I purchased a 99 4.3L Chevy vortec and matching 4L60e transmission with 22,000 miles on it. I am 80% complete with the install in the jeep and have saved the best for last. I am not mutch of a mechanic so be patient. I need help / ideas with the wiring harness and computer. My brother-in-law is a mechanic and helped me up to now. Would like to perform the conversion without purchasing a $700 adapter harness but I will if need be. Any thoughts would be greatly appreciated.

James
Splice what is needed through the bulkhead connector. See if you can get on ALLDATA. You can get wiring schematics there.
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Unread 04-14-2010, 01:59 PM   #3
jasman
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1995 YJ Wrangler 
 
Join Date: Apr 2010
Location: florida
Posts: 3
Thanks for your reply. Like I said, this is a first for me. How do I know exactly what I need. I have been told I have to connect 1 wire from the ignition to the computer of the new motor. I know I have a speedometer, odometer, fuel guage, temp guage, oil pressure guage that need to be connected. The break system is hydrallic so that is not a factor, I don't have ABS, so that does not appear to be a factor. Is there anything else from the engine or computer that I need to think about?

1989 Wrangler YJ thanks for your response.
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Unread 04-14-2010, 02:19 PM   #4
Alfons
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1992 YJ Wrangler 
 
Join Date: Jul 2005
Location: Ontario, Canada
Posts: 2,218
If you have the engine, computer, and engine wiring harness (including all under hood components like the power distribution panel), you have almost everything needed to make your life simple. I always recommend that people take the cabin-side firewall connector half along with a few inches of wiring so that you have something to splice to, now you'll need a detailed pinout of the Jeep and new motor harness firewall connectors to determine what you need to splice to what. I cut off the Jeep connector after marking each wire and then mark each wire on the new-engine connector. Now splice these wires, function to function - you shouldn't have any "important" wires left over on either side and these can be addressed one at a time. The critical set of wires will be those that allow you to turn the power on with the key switch, this will power the computer etc.

Depending on how the new-engine wiring harness was put together, you might need some creative splicing for things like headlights, fuel pump, etc, but if you have the connector pinout descriptions for the new-engine harness and the old jeep harness, you should be able to see exactly which wires to cut and where to splice them - it's no different than plumbing.

I would offer you some diagrams but the oldest I have for the jeep is '91 and the newest I have for a GM truck is '96. If you can get some diagrams that represent the correct jeep and new-engine connectors, I can help you with what you need to do.
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Unread 04-16-2010, 09:31 PM   #5
jasman
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1995 YJ Wrangler 
 
Join Date: Apr 2010
Location: florida
Posts: 3
Thanks for your help. I just purchased "Alldatadiy" data for the 99 4.3L and the 95 jeep. I will be looking at the pinouts and give it a shot this weekend. I'll keep you informed. I think I still need to send my computer away to be reprogrammed or so I've been told. Any thoughts?
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Unread 04-17-2010, 10:13 AM   #6
stoveguy01
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1989 YJ Wrangler 
 
Join Date: Mar 2008
Location: Bonney Lake, washington
Posts: 193
ive done simular swaps best this to do is really study your diagrams. find all your wires marked constant power, switched power (run,start) find your gauge wires and so forth than with the new harness on the grouns locate said wires and mark them this is easyest ive found with a digital multimeter set to ohms and and alarm. put one lead on a known temination point an example your starter wire than start checking alll the cowlplug wires or loose wires tell multimeter chimes. than mark it using masking tape and what it is. do this tell everything on the harness is marked before even attempting putting in the jeep. than do the same to your cowl plug on the jeep. mark your constant power and so forth. Now you install it in your jeep and life is alot easier. I just installed a 94 grandcherokee 5.2 with 4 spd auto into my 89 carbed jeep done the whole swap in 3 days and was driving again never had a problem doing a swap this way and ive done a few. good luck
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