A wiring question? the dreaded c101 connection under the hood on the 88MJ

[Submariner]

I have been lucky enough to acquire the wiring harness from an 89MJ that has a 4.0 engine.  It does not have the c101 connection.

 

I was wondering if I could plug that into the firewall box in an 88MJ that has a 4.0 engine.   If it would be compatible then that would eliminate the c101 connection above the box.  And I would not have to cut and splice all those wires.

 

Has anyone done this or thought of doing it before?  Do you think it is feasible?

[PhilisDiller]

I'm sure it's feasible. Unless you have concerns about the quality of your wiring all the way through, I would definitely solder eliminate the C101. Took me about an hour and a half. Also, you can eliminate some of the shoddy ground crimps that they do from the factory. I would imagine that a harness swap would probably take 3-4 hours at least. What's the reason you want to swap? What's your ground resistance at the MAP and your ground resistance at the O2 sensor? 

 

I think I've seen different dash clocks throughout the years so you'll probably have some issues there. 

[89 MJ]

Pulling a whole engine harness is a royal PITA, don't do it if you don't have to. It will take you forever. When I did the engine swap in my blue truck, reinstalling the wiring took the longest.

[watchamakalit]

I went thus route due to the condition of my harness. I went through the harness on the bench and made all necessary repairs and upgrades before swapping into the truck. Actual swap only took a couple hours and that wasnt trying to rush. I used a xj auto trans harness w/o c101. Now have the option of the auto swap if I desire. 

 

Edit: forgot to say. If you have time to be able to source and repair the harness I would recommend this route. Lets face it, every connector in the harness needs cleaned and ox guarded anyways. What better time and method than installing a "new" repaired harness. If you need the truck running quick I wouldnt be afraid to cut/solder to remove c101.

[Ωhm]

If your goal is to eliminate C101, then just replace the Engine Control Harness and the Injector Harness. Leave the Engine Harness still in place.

[Submariner]

3 hours ago, 89 MJ said:

Pulling a whole engine harness is a royal PITA, don't do it if you don't have to. It will take you forever. When I did the engine swap in my blue truck, reinstalling the wiring took the longest.

I was going to do this when I swapped engines and transmision and install a transfer case for the first time.      I am taking out a 4.0 2wd ax15 and install a 4.0 4wd ax15/transfer case.

 

Also I am changing the front fenders, doors, and grill from a 98 cherokee.

 

I figured I would also replace the headlight wiring also. and install a tilt steering wheel with cruise control.

 

Not going to do much stuff to the ole girl in the next few months   HA FK HA

 

 

[Submariner]

2 hours ago, Ωhm said:

If your goal is to eliminate C101, then just replace the Engine Control Harness and the Injector Harness. Leave the Engine Harness still in place.

I think that is what I meant.  maybe did not say it that way.

[mjeff87]

100% yes.  I used an 89 engine harness sans the C101 when I converted my 87 2 5 MJ to 4.0.  It was completely plug and play. Zero issues