Help with wiring harness

[Battmudd]

Bought what I believe is a 4.0 motor and an ax15 transmission last year to swap my 2.5 out and put a 4.0 in. I believe the guy who I Baught it from gave me the wrong harness. Any help on with harness to purchase to fix this issue would be helpful. Thank you

 

[Walt Jaquith]

You've got a fuel injected engine, and I believe I can see the plastic rail for the plugs for the injectors in the background. As long as there are six injector plugs you should have either a 4.0 or 4.2 EFI harness. I have heard that there are differences between them, but haven't seen anything to confirm it. The harness should cumulate in a large plug for the ECM. Did the ECM come with it? You'll need one, and they're getting hard to find.

I would download the YJ wiring diagrams and start tracing some wires by their colors. That's a fast way to tell what connectors are supposed to go where, and you can match them up to components on the engine. On page 8W-75 there's a list of sensors, and that would be a good place to start. For instance, for the 4.0 the throttle position sensor has three wires; Black/Light Blue, Orange/Dark Blue, and Violet/White. Find a connector with wires that match that, tag it, and keep going. You'll need to be pretty familiar with all this to get it working.

Good luck. It's a big job, but the satifsaction when she finally runs is pretty cool.

 

[Walt Jaquith]

Additional: It would be good to identify the engine precisely. The 4.0 has had a lot of tweaks over the years. Found this in another place:

All 4.0L have a casting number cast into them on the drivers side near the motor mount bracket. XJ engine blocks also have a build date number identifying when the bare block was built into an engine.

Block Casting Numbers

Year............Casting No
1987-90......53005535 (8933002665)
1991-95......53008405
1996-98......53020569
1999-04......53010449

 

[Flyer58]

Those intake manifolds crack me up. I bet the whoever designed it wasn't getting paid.

 

[Battmudd]

Thank you for the help, I’m just confused because the connectors on the wiring harness don’t match up with the connectors for the sensors if you can see in the pictures

 

[Walt Jaquith]

Those intake manifolds crack me up. I bet the whoever designed it wasn't getting paid.

There's actually some reasoning there. They went with port fuel injection instead of the cheaper and easier throttle body injection that everyone else was using at the time because with a straight six it's impossible to get the runners to each cylinder the same length, and with fuel suspended in the air, that makes for really uneven performance between the cylinders. Even with just air, it's important to smooth out the pulses and turbulence between the cylinders. If you look at the intake manifold of a modern rig, even the V6s and V8s do the same thing. They look a little more elegant, but they have a main chamber that the air comes into, and all the runners for the cylinders are the same length and shape. Given the year it was designed, it's possible that the Jeep's intake manifold was designed on a drafting board. Not so easy to do something with a bunch of swoopy shapes.

 

[Flyer58]

There's actually some reasoning there....
View attachment 116099

Yeah I can't disagree because that's how they were back then. Look at some of the early 60's 6cyl Ford's and the they have a similar intake with 2 or 4 barrel carbs in the center. That fuel must have been slamming and pooling onto every corner. Don't even look at their exhaust, it a straight tube with a central outlet

I'm just glad to see the improvements. The new Jeep has a V8 392 cu in with 450 HP. Compare that to the 304 cu in V8 in the 1980 CJ with a whopping 125 HP.

Didn't mean to highjack Battmudd's thread carry on

 

[Battmudd]

Thank you for the help making progress now. Ok so it is a 4.0. Block numbers read - 53010449. They gave me the wrong harness and computer. As you can see pictures the male connection ends don’t match the female. This is an ego engine. Any help you’ll be appreciated Anybody know someone trying to sell a harness that’ll work with this motor? I am also going to need the bell housing bolts to attach the motor to the transmission. 4.0 motor ax15 transmission out of a tj Or a Cherokee I believe