Joah

Purchased a 94 ZJ with 4.0 and a 93 ZJ parts vehicle.

I swapped in the AW4 along with all component harness (including flywheel sensor). TCM and PCM is a direct swap with engine harness from the 93 into the 94.

I readjusted park cable. Everything is a direct hook up from 93 to 94.

But ... no start.

I get 1 2 on the diagnostics and about 30 seconds later the red security light comes on in my instrument gauge. It'll crank over but no start.

I use the key in the driver door to disable the alarm and it stops blinking.

When I first put the key in the ignition, the engine light comes on faintly, then I put it to the start position and the engine light goes on for a bit and then it goes off.

This project has taken me a month by myself. I am proud of my accomplishments so far, but am still left feeling stuck under the ice.

I'm going to go try and open/close all the locks and press the unlock/lock button three times. I just feel like the planets need to align for this to happen ... ever feel like that? It's like a primal challenge, rage vs. the machine. I think I am composed, although there's a part of me (maybe my blood pressure) that just doesn't feel right.

So yeah, in my opinion those 93 parts should work in the 94 as they are all part of the same harness and the engine is the exact same. Unless there's another computer somewhere,

My guess is that the pcm is not happy with something ...

Did I miss anything?

ol"blue

Welcome to CF.
You need to close all doors, and using the key lock then unlock the passenger door to disarm the alarm.
The AW4 has a TCM under the dash by the steering column support, while the 42RE's TCM is different, but in the same location. Did you get the TCM from the '93 and hook it up? If not it won't shift properly.

stomper27

its easy to dwell on the negative... I do it too much.

Any ice you're stuck under its pretty thin, but from where you are you can't see the thickness (wow my first metaphor)

Stay with the positive, and post some pics when you've solved it. Would love to see another 94 ZJ - I'm a new first time owner of one myself. Good luck!!

Joah

Thank you for your response. I have a feeling that I will be at this one for a long time. I really want to accept this final stage as a great passage in my life. I know that I should be rewarded for the past 100 hours I have done in replacing *all of the necessary components, and I am fighting an urge to become depressed over this. This is just how life is. Anyhow moving on ...

I have replaced the TCM from the 93 and bolted it in its place. I've replaced the complete engine harness. It is one assembly comprising of the engine hook-ups: carb, injectors, distributor, flywheel sensor, etc and two AW4 hook-ups. I have replaced the PCM from the 93 as well. All are currently in my 94 zj.

My project jeep is at my garage located 30 blocks away from my computer. I'll go over some of the things that I think might be causing problems. There is one plug at the middle top of the AW4 that is disconnected. I can not find the missing connector. I had *help starting the project and my friend disconnected a bunch of stuff then he booked. I checked on the 93 parts vehicle and there's no wires left. This is the picture.

I also broke the transfer case rod and as the 94 rod has a slight bend to it, I have not installed this, although I don't believe it would affect start-up. This is a picture taken underneath the AW4 about midway:



This is a plug that is attached to the TCM harness underneath the dash, it was disconnected on both harnesses and I have no idea what this plug is for:



After I leave the key in the start position in the ignition (but not cranking it), the engine light comes on then goes off, seatbelt light goes off, airbag light goes off. Then two minutes later (still key in start) the security light goes on:



I tried my key remote and it does nothing. I don't know if it did work before (as I purchased the vehicle a couple months back and don't remember).

I tired unlocking the door with my key and it does stop the lights from blinking. I tried unlocking all doors and hatch three times and lock/unlocking the power locks from inside.

I tried removing the positive and touching the negative to clear capacitors then place key in on, turn lights on, turn lights off and place key in off position.

I still get no startup.

I can hear the fuel pump working, it sounds like a faint grinding sound coming from the rear (underneath). It will stop making noise in a second.

I don't know what else to do. BTW, I was getting the same problem from the 94 PCM, that's why I switched to the 93 PCM thinking it would be happy with the old setup.

I have read that I can cut a purple/yellow wire at the driver side kick panel, but I looked for this wire and cannot find it. I have taken pictures in hopes that someone can help me find it. I really don't want to cut this wire, but I don't really want to give another man $1000.00 to fix this needle in a hay stack. I just don't know what else to do. Do I dissect the other 94 harness and rebuild a complete harness for the AW4? Do I approach an automotive technical school with my problem? NASA maybe?

Anyhow, maybe someone can help me locate that yellow/purple wire. Here are some pictures of the bottom left underneath dash:



Very bottom:



Also, I remember a small difference in connecting the tcm harness under the dash. The 94 harness had a small two prong connector that the 93 did not have. I took a picture of this missing connector plug in:



So yeah, that's all I got,

Thanks, and if you read all this, well, you feel my pain.

Bustedback

Thist is the windshield wiper delay module.

Joah

Do you think I might need to flash the PCM at the dealership?

I was thinking that maybe I need to swap out the computer in the top console, and maybe there's a computer at the center console that I need to swap out?

That security light is probably there for a reason. Stupid computers, our reliance on them makes us into jello.

Joah

Okay, I spoke to the dealership and 93-94 do not require flashing as I think this has something to do with OBD I.

There is a Security Alarm Module located behind the glove box. I swapped in the 93 SAM into my 94 and disabled the alarm, them removed the SAM completely. Now there is no more "security" light going on.

Alas, I still cannot start this vehicle. '

So I hired a mechanic to come have a look and we were able to determine that there is no spark! The coilpack has 12V going in but on 3.8V going out. So we swapped out the coilpack with the 93 and still getting the same results, 12V going in, 3.8v going out: not enough to spark.

So we figure that we are losing power from the harness. This guy figures that it may be the crank sensor. He says that maybe if it gets bumped even slightly it may become damaged. So, I took it out and tomorrow I will try and buy another one. Is there any way to test the crank sensor? Nobody knows.

He did set me on the right track. I had to give him $60.00, but I found $5.00 on my way to the bank machine, and he gave me the idea how to check what the problem is. All along I've had my mind on swapping in components, the TCM, PCM, harness, SAM ... now I have to take out my volt meter and possibly arm myself with a proper schematic.

I don't even know how the crank sensor works, there are slots in the flywheel and probably a magnet in the sensor that places a resistance when the flywheel is closed and allows current to pass when the flywheel is open. That's how I imagine it works.

Sigh,

Joah

I'm just racking my brains here, does it matter how I put in the flywheel? I mean did the torque bolts have to line up in a certain sequence> I'm just thinking crank sensor ...

ol"blue

This tells how. Hope it helps.

Joah

Thank you. I am going to replace the sensor today. If this doesn't work, then I'm going to do some deductive reasoning with my volt meter.

That book people are showing me is popular, (I think it's Hanes Manual?) yeah, it is a pretty good book, but it doesn't have important stuff like engine/tranny wire harness. I think maybe Chilton might have? I'll have to take a walk to my downtown library and dig up the harness, that or pay a visit to my dealership ...

... the adventure continues ... will the dedicated hobbyist survive ... will the mechanic he called continue to swindle people with his curbside advice ... tune in for the epic saga of 93 AW4 vs 94 RE42.

Joah

Well, we did not install the rubber grommet for the crank sensor. This is the fail of having someone start your projects, but not help finish. So, I have no idea if this is the problem, but I will install the rubber grommet for the crank sensor regardless.

Other than that, I traveled to my library and they had a plethora of mechanical books dated back to 1980, and diminished rapidly when we hit 2000. I think this is a statement of modern man, as in 1980 there were more people who would work on their vehicles, it was an accepted norm. Today, everything is delegated to the technician. Now I must seek a technician and his lore, most likely to be found at a dealership.

Cheers,

ol"blue

Try this: Jeep ZJ Wiring diagrams
It might help you out.

Joah

Aarg! My local technical school has 1 book for rent in their library: 1994 Grand Cherokee Service Manual. The gods are mocking me!

Joah

On the plus side, my neighbour who's also my friend own a 1993 ZJ. I had a look underneath and that mystery connector is also unplugged ... in NY!

ol"blue

Did you look through the wiring diagrams in the link above?