4.0 MPFI harness help (XJ motor in a Scout II)

Hello,

I was told ny KSXJ that this forum has many folks who are very helpful and that I can possibly get my questions answered here.

I am doing a 4.0 head and MPFI conversion, on a 1972 Scout AMC 4.2L. I have the conversion part down but need a little assistance on the harness.

I did an adv search and came up short. I am doing the entire build of the vehicle from the frame up on you tube. When I do the head mod episode I will be doing a step by step of the engine harness swap. So, hopefully all these questions will help other Jeep and Scout folks in the future.

But, before I can start to put the videos together I must first learn how to do it myself. So I am on a fact finding mission and I would like to ask y'all a few questions...

Info: Motor is from a 1994 jeep xj Cherokee. I have the entire harness and the computer, plus sensors ect.

A. Think I have this one right as well but I am unsure of what plug 3 is:



B. here I have:
1) Plug1:
2) Plug 2:
3) Plug 3:
4) Part 1:


C. White Plug:
1) Black Plug:
2) Blue all weather plug:
3) 3 mystery wires:



D. More plugs to ID here:
1) green 2 pin all weather
2) red stripe 10 pin
3) black 6 pin "L" plug



E. Ouch time...Oh good grief I am gona have to look for large weather proof connectors I think. Yea I did this when we were taking it out. I mistook a part in the engine comp for the computer...we later realized the error in my logic.



F. More Wires I cut... this was the big no no. I realize i am going to prob have to chase em down but maybe someone will have an idea.


I basically plan to lay this harness down, clean it up and then start removing the stuff I don't need.

Well that's about it for now. Thanks for any help you folks can give.

Plz excuse the low rez. Had wifes camera for the week and did not realize it was set to such a low rez.

I also Have the right year factory repair manual and wire diagrams for the XJ so naming these plugs will help me ID them better.

N2IHC

I actually swapped a 4.0 into a Scout last year. If you can get everything plugged I just left all other wires in the loom and cut back all the loose ends and it looked pretty clean. I just grounded the computer and hooked into where the Cherokee ignition switch wires hooked into. If I remember right it was just a 12v switched, a constant, and a main power going to the computer what was a heavy gauge wire. If I hadn't sold this thing I would go get some pics for you.
Here is a pic of the Scout and yes it is Pink.

Sounds like fun. Wish i could help but I have a Renix system lol. Did the Scout originaly come with 4.2 or was it swapped? I'd like to see the resto videos, good luck.

It's been real fun so far. Oh, and from 72-74 it was a stock option for the Scout II.

I believe plug 3 is for the crank position sensor. You got some serious wire splicing to do. If it were me I would get a whole other wiring harness from the JY and make sure it is not cut.

jeeperjohn said:

I believe plug 3 is for the crank position sensor.

Click to expand...

Awesome thanks!

jeeperjohn said:

You got some serious wire splicing to do. If it were me I would get a whole other wiring harness from the JY and make sure it is not cut.

Click to expand...

Wish they were easy to come by here, I would. I cut it at the fire wall anyway so it should be okay. I needed a excuse to buy a pin crimp tool any way. =p

Also, think I figured out that pic (C, 1) is the NSS plug.

Why can't you edit posts here? Did I miss that in the FAQs?

you can edit posts for like 5 minutes. its disabled beyond that to prevent internet schenaneghans.

cool project, thats all ive got to contribute though.

I see i am stump'in a lot of folks. What's the best way to go about fig this all out. Should I just start tracing wires? My biggest concern is what circuits I need to keep and what crap I can toss.

well I believe #3 in ur very first picture goes to the CPS that connects on the transmission housing. I'd have to go look at the 94 I'm parting out to double check. I'm used to renix but I think they are the same there.

On ur 4th picture that looks like the 2 pin green one is the connector for the electric fan, I've spliced into a few of those when the censor wasn't working. The 10 pin red stripe one looks like the header panel light harness. Think that's all I got to offer for info.

You're going to need to swap in a flywheel and bellhousing from a 4.0 vehicle to mount the crank position sensor, or get one of the harmonic balancer mounted ones (which are intended for this type of swap). You'll have to splice that plug into this connector:

http://www.hesco.us/shop.asp?action=details&inventoryID=148640&catId=

The best guaranteed way to get all the wires correct is to buy an FSM for the donor year on ebay. Chrysler books are pretty good, every wire has a unique color/stripe pair and they are listed by color and gauge in the electrical section. We're friendly people but nobody wants to transcribe the FSM

Got one already. Wasn't sure if the book was going to tell me like "2pin green all weather connector" Ect. On an IH all wires have numbers. That can be good and bad. bad if the harness is old and the numbers have come off or the PO got happy with the diag cutters.

I'll just have to start snoopin around in the book and fig it out. If I hit a real brick wall I will come back.

Wish me luck! =)

cal said:

You're going to need to swap in a flywheel and bellhousing from a 4.0 vehicle to mount the crank position sensor, or get one of the harmonic balancer mounted ones (which are intended for this type of swap). You'll have to splice that plug into this connector:

http://www.hesco.us/shop.asp?action=details&inventoryID=148640&catId=

Click to expand...

That's exactly what I planed to use. =)

PIC F appears to be all the wiring going to the under hood fuse/relay box. That there is going to be a lot of fun to play with. I'll try and help you out as much as I can and take pics of my wiring for reference.

I have a factory service manual in you pm me your email address I can send you any wiring diagrams you want for the jeep harness. This is how I decifered mine when I swapped it into my Scout.

I got a FSM for the 94 jeep thx though. I also got some good info looking at painless's site. It's nice they have their directions for free. I always suggest them to folks who hate to build their own harnesses cause of that.

Started cleaning the harness up today. Wow it's filthy. Going to label it all with a P-touch machine.