95 ZJ 4.0 into a YJ wiring - Pirate4x4.Com : 4x4 and Off-Road Forum
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Old 08-09-2011, 07:40 PM   #1 (permalink)
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95 ZJ 4.0 into a YJ wiring

Anyone engine convertion on a 95 yj with a 2.5 to a 95 ZJ's 4.0?

The wiring harness is completely different than the YJ 4.0.
Would this swap be easier to use the instrument cluster from a ZJ instead of trying to make the YJ gauges work?
The things I'm worried about is keep this easy for diagnostics, passing smog with check engine light & the next owner. Oh yeah & the auto tranny working correctly.

Or just get the engine harness portion from a YJ 4.0?
YJ, 3.5" lift, 33's, locked frt/rear, 4.56's, full cage, 1 bandaid 4 emergencies

Last edited by Jabird; 08-11-2011 at 10:20 AM.
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Old 08-11-2011, 10:19 AM   #2 (permalink)
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YJ, 3.5" lift, 33's, locked frt/rear, 4.56's, full cage, 1 bandaid 4 emergencies
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Old 08-11-2011, 07:48 PM   #3 (permalink)
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From what I've read on 2.5 to 4.0 swaps, get a PCM from 4.0, add 2 wires each needed for #5 & #6 injectors (that's the only difference between the 2.5 and 4.0 harnesses, apparently). If you're worried about it, get a 4.0 engine-side harness and plug it all in. 92-95 will work for you. 91 uses mechanical speedo still and I"m not sure if that's in the engine-side harness or body harness so I suggest 92-95 only.
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Old 10-13-2011, 01:23 PM   #4 (permalink)
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I am in the middle of swapping a 4.0 from a 95 ZJ into my YJ also. I have read about just taking 2 injector wires from the 4.0 ZJ harness and adding them to the 2.5 harness bam done , but how is this done? do you just drill out the the pins push the wires in and put a few drops of solder in or is there some special connector plug you can buy? I have the harness from the YJ 2.5 and the one from the Zj. I also thought about cutting the 2.5 connector that connect to the firewall and splicing it the the ZJ harness ,But just adding 2 wires to the yj harness seem like it would be alot easier and have less possibility of failing;if it is that simple. Thanks And good luck with the swap.
92 yj soa 35's ax15
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Old 10-13-2011, 07:24 PM   #5 (permalink)
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There are some differences in the bulkhead wiring connector and other circuits between different years of YJ's. Easiest thing is to get a 4.0l YJ harness the same year as the chassis.

Next easiest would be to add the two injector wires, and shorten/lenghten any 2.5l wires that won't reach, they will plug into the 4.0l components if they are from the same year, therabouts.

If you look at the Mopar OBD-1 SBEC 60 pin PCM connector, you will see a red plastic insert on the computer side. There is a black plastic retainer on the wire side that holds in the silicone water seal. Unsnap the retainer for the silicone seal, pull the silicone seal back with a small screwdriver about an inch or two. You probably will need to strip off the sleeving and tape from the harness.

Now remove the red plastic retainer.A small screwdriver will pop it straight out. This red piece keeps the retainer tabs from releasing the terminals in the connector.

Match up the #5 and #6 injector circuit terminals you need to add to the 2.5l connector in the ZJ connector. With the retainer removed, you will see a little tang that retains the metal terminal into the black main connector body. Pull the tang sideways a bit with a pick or tiny flat blade screwdriver, then pull out the wire with the terminal attached. Work it through the water seal and carefully strip it out of the harness all the way to the injector connector. You will find that one of each of the injector wires are spliced into a common power circuit. Clip them out, you will need to splice them into the same wire in the 2.5l harness.

On the 2.5l connector, there will be two plastic plugs in the position of the two added injector circuits. These will simply be in the silicone water seal. Pull them out with needle nose pliers or push them out with a probe.

Make sure you are connecting the wires into the proper location, then simply push them through the seal and retainer, then into the main body until they click. Once you are done moving things around, reinsert the red retainer to lock them in place, and reinsert the seal and it's retainer. Retape the harness sleeving and you are done!

Probably would be good to swap over all of the ZJ circuits that go to the intake manifold and throttle body areas. Take your time to get them into the proper locations, and you won't have a butchered up looking harness after you are done.

It really helps if you have both wiring diagrams, and pinouts for the connectors: one for the donor, and one for the rig.

Hope this helps!

P.S. The local Mopar dealer sells a wire repair kit for the connector with a number of terminals already crimped to about a foot of wire. Handy for adding circuits when you don't have a donor or if you have a suspected loose terminal making a poor connection.
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Old 03-05-2013, 08:17 AM   #6 (permalink)
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I'm doubt the same swap a 1993 jeep grand Cherokee zj 4.0 with a 42re auto transmission. I also have the PCM from the zj. I'm putting this in a 1995 jeep yj. Could I use the bulkhead plug that connects on the firewall. I know the wires have to be switched around bulkhead connector. The question is which wires could you help me with that
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Old 04-01-2013, 01:46 PM   #7 (permalink)
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93 zj 4.0l /w aw4 trans into 92 yj /w 2.5 and 5spd

k guys here we go, and remember Ive done this it works.. you must have comon sence to do this

first pull your zj engine take with you the whole harness from the engine bay + the tcu from up on the fire wall on the inside of the jeep. once its out the harness should be mostly complete with the tcu, pcm, injectors, and all plugs for the various sensors. you want to locate the plug that sat above the pcm in the engine bay its oval and looks like it comes apart cut the wires off the pcm side of the connector. find yourself an xj pcm!!! use schematics for the model engine xj the pcm is from! and lable all the dead wires via the pinout on the pcm. DO NOT CONFUSE THE WIRE COLOUR!! USE THE PIN OUT!! you should have about 15 or so wires. place off to the side

take your 2.5l harness and cut away the injectors and you will be left with a bulkhead connector fuse box and thru hull gromet and the stock pcm connector, now as you cut the wires off the pcm connector use the pin out for the 2.5L engine to label the wires you cut off.

have a friend help you if you are un-sure about anything!

once these are all labled pull out your hacked and labeled 4.0l harness splice together all simmilarly labeled wires from both harnesses! DO NOT WORRY IF YOU END UP WITH LOOSE WIRES! there will be a few.

now that thats done take the harness to the truck plug it all in.. there shoud be tps, map, crsps, distributor, oxygen, pcm, tcu, and bulkhead connectors you shoud knowtice at this point that you are missing an ignition wire, selonoid, and one red power wire,

first the red power wire needs to be connected to switched power, this will give power to the pcm and injectors all at once, pretty sure I used a relayed power. but its a low draw so it shouldnt matter. you will find the plug for your ignition just on the other side of the funny connector in the zj harness, and the wire for it shoud be labeled ignition.

finally you should have one last dead wire. this should be your keyed solenoid power, connect and test!

Good luck!

if you've made it thus far you should have no problems!

89YJ SOA+2.5" procomp springs zj 4.0L/w reclocked aw4 and np231 hackn tap tom woods driveshafts.. pending a toyota minitruck axle flip & swap finally 33" interco thornbirds.. four years countless hours all for a six hour trip once a year!!! :P

Last edited by Be Radical; 04-01-2013 at 02:16 PM. Reason: put in my tag
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Old 04-01-2013, 01:47 PM   #8 (permalink)
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check your trans some zjs of that year come with aw4
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Old 04-01-2013, 04:28 PM   #9 (permalink)
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