CognizantPotato

Thanks for the tips guys. I think I managed to find and label most of the suspect wiring, so I’ll be trying to improve that a bit. I’ll also be trying to clean the fuse box soon. I’ll update as soon as I have any news to share.

Do you think that this would work as a replacement?: https://www.summitracing.com/parts/prf-30001?seid=srese1&gclid=CjwKCAiA1eKBBhBZEiwAX3gql9aC11_aWGMkK-GcoUZDxQJ2L2gB89to3ffV0kq9_q3Vcqi8bYDdohoCM_EQAvD_BwE I feel like I'm going to have a hard time finding an mj/xj around here to get parts from.

How did you replace it? It looks like I’ll either need a new harness or need to splice all the old wires to a new box.

I didn’t even notice the melting there. Thanks for pointing that out.

Hi everyone! I’m back on the forums. A last year I was having problems with my mj. I gave in after a while and took it to the mechanic. He replaced the ecu and fixed a bad wire. Well that worked for a few weeks, until the truck died again and it seems as though the computer has suffered damage once again. The truck was acting odd with things such as blinkers not working, ac blower motor cutting out and then back on. I realized that me applying pressure to the fuse box and shifting it made things work every now and then. After the truck quit I was too frustrated to do anything else with it and it’s sat for months. I’m finally getting around to trying to fix it, and fix it right this time. I’ve taken the dash out and have removed the sleeving from all the wiring. Whoever worked on this in the past did an awful job. There is duct tape in several places covering wires crimped together, so I’m setting about cutting and soldering to make sure my wires are clean and connected. The fuse box acting weird is still making me concerned about it’s health though. I have attached pictures, and would love to get opinions on it. Is it simply old dielectric grease, or does it look like there may be some sort of corrosion? Any help would be greatly appreciated!

As the title says I can’t separate the fuse box connector from the engine side. I’ve loosened the 1/4” bolt but it won’t come out. Ive tried to pull them apart with the bolt loosened, but have had no luck. Any idea what’s going on?

Thanks for all the replies everyone!

Hi all! My 1989 Comanche has recently come back to life and is running great, but there are a few things I would like to do at some point in the future. I love the manual, but honestly just enjoy an automatic more, so I was thinking of having a swap done. I also would like 4wd in my MJ. These are not things that I plan to do any time in the near future, but would like to possibly have done some day if I keep the truck for a while. Does anyone have a list of everything that would be needed for a manual 4x2 to automatic 4x4 swap? Would it even be possible or feasible in terms of cost?

Update: I took the truck to my mechanic a while back because I started back to college and didn’t have time for it. There was one wire in the harness from the ICM to the computer that was naked and sparking. It burned up the computer and some other components. The mechanic fixed it and it came back home today working great! Thanks all for the help!

I have checked directly from the coil. I have a few ideas that I'm going to test out tomorrow. I'll update if anything new is found!

Yep. Everything looks clean. Just to make sure I sprayed it with some electronic cleaner

Update: I have a new CPS in that’s reading correctly. It should be working, but still no spark. All grounds that I know of are good. I’m getting 12V to ICM and 10.5V while cranking. All test on the coil seem to indicate that it’s good. Any thoughts now?

Are you selling them? If so how much are they?

Update: Today I’ve been cleaning grounds and connectors. I did test the CPS again using AC on the voltmeter and only got 0.3V

I’ll make sure to have completed steps 1-5 this weekend. I’ll also try and get a pressure gauge to verify the fuel is okay. Thanks for your suggestions!

I feel like an idiot now lol. Yep I was measuring DC. I’ll have to go out tomorrow and test that again.

Thanks for the tip. I’ve tested for spark that way. I know it’s getting fuel. I’m a bit skeptical that a new CPS wouldn’t work straight out of the box, but I know how aftermarket parts can be (especially cheaper ones)

I tested the CPS again today. It was still spiking to 0.7V while cranking, but I kept getting infinite resistance between A and B. Could this be a problem or does that sound normal? If this isn’t the problem I might have to start tearing the wiring system apart and starting from scratch lol.

Yep I can hear the fuel pump. I’ve checked the grounds too and cleared them off. I’m beginning to think the female side of the cps connector may have been damaged due to the deformation of the first CPS connector.

Okay I’m getting full voltage on D1_5 and D2_4 On D1_6 I’m getting about 10-11V while cranking

Still can’t get the engine to start. Any more ideas?

Update: Installed the new MAP Sensor and still nothing I'm wondering if it’s not just a faulty cps still. I’m going to try and test it again

Ah okay that makes more sense now. Thanks! I’m replacing the MAP sensor tomorrow so I’ll update and let everyone know how it goes

An update for today: I’ve checked the connection to the ICM and there is a full 12.5V going into it. There only seems to be around .75V to 1V leaving the ICM going to the ECU. I just replaced the ICM though, and the ECU was replaced very recently too. Is this small voltage normal, or does something sound wrong there?