A couple months back I picked up this xj that wouldn't start not knowing anything about Cherokees changed the 30 amp ASD fuse and drove it a couple thousand miles. Back in november it stalled while driving then would crank without starting. I got it running again by disconnecting the front o2 sensor and drove home. The next day I tried changing the o2 sensor but I couldn't get it off so I drove to the autoparts store to get some stuff to convince it to come off and on the way back from that trip it stalled while driving and wouldn't turn on again. I switched the asd fuse and it no longer would blow. This time I rolled into an auto shop and took it as a sign. Now its been several months and probably just been ignored. The diagnosis Ive gotten have been a bad pcm then replaced and shorted again to then be diagnosed as a bad engine harness. I'm not sure how much I could believe these diagnoses though since when I look under the hood it doesn't seem like anyone has been there (they said they changed the o2 sensor then didn't).
Now the car is back in my hands and I'm struggling where to look for this issue. The engine harness doesn't look too bad though other wiring harnesses in the car look terrible. I'll put some pictures of the wiring attached but the only thing interesting I've noticed is the main ground of the car. I'm honestly worried to try starting the car since the new pcm was expensive and id rather not short another. I've also replaced the cps, rear o2, and cam position sensor. Any advice would help
I've also ordered another engine harness but I don't want to just chuck it in hoping it works.

 

1)it always helps if you àt least tell people what model year it is.
2) those are about the worst looking battery cables/clamps I've ever seen. They could be the cause of all sorts of problems.

3) you need to do a lot more diagnostics/fixing the easy/cheap stuff before you throw anymore parts at it.
Battery cables, probably a battery, do all the grounds etc

 

Ah that's my bad its a 1996. Is there somewhere I could find the locations of all the grounds? I've wanted to test them but I'm not sure how to go about that. I've also thought the battery cables sucked but is it possible to just replace the battery cables? Thank you again I am really stuck here

 

With all respect I think you may have bitten off more than you can chew with that thing.

But if you're going to attempt to learn enough to work on it:
find a free download of the factory shop manual, Haines etc are useless.
And to answer your questions
You don't trust the grounds in a situation like that, you just assume that they're a mess. , you take them apart, clean them to bare metal, put them back together.. couple dozen of them.
Of course you can replace the battery cables/clamps

And never go back to the shop you used.

 

I probably have bitten off too much but it is a kinda project. I want to keep going purely because the time I spent with it running. I'm going to try all that and try to use a short circuit finder to see if that works.
I think I could ignore the shops diagnosis since as I look more into the car it seems like nothing has changed other than the PDC being opened up.

 

These are the main ground locations I know of. I have a renix, so there will be some differences.

1. There is a ground strap that runs from the driver side rear of the engine block, to the body.




2. Several important things are grounded at the dipstick. The oil dipstick mounts to the the engine on a stud that it shares with many grounds.




3. There might be a cable running from the negative battery clamp to the body by the passenger fender.

 

Thank you for those pictures. I probably need to clean the studs for the battery cable ground on the engine block

 

What is the voltage of the battery?
Have you pulled a spark plug to see if it's firing?
Is gas getting to the fuel rail?
If voltage is good and it's turning over with gas flowing and spark plugs firing, then test the sensors ( get a shop manual and a VOM to do this)

 

I haven't done tests since I got it back purely cause I don't want to fry the PCM like last time but before I sent it to the shop there was no spark and there was good fuel pressure. The shop also gave the car back to me with a very dead battery so I am still waiting for it to charge back up. Its got a new ignition coil, distributor cap, plugs and plug wires though since when I started driving it they were very old.

 

Testing your sensors will not hurt your PCM. This is my drill, because I'm bad at guessing - get your shop manual. Assuming your air filter is clean, spark plugs, cap & rotor and wires are good, check for dangling wires grounding. The wires coming up from the O2 to the fuel rail wiring harness are a good place to start. Then open your shop manual and test your sensors: the temp sensor, idle solenoid, MAP and TPS. In my experience, the crank position sensor is good - or you stranded by the side of the road - but test it anyway. If they are good and your throttle body is clean, move to the injectors: clean them and test the resistance for each one. You can pull them and use a 9v battery to produce a click unless it's defective.

 

When I get some more time (its been really cold) I will definitely do sensor testing. What I did find today was my circuit tester stopped making noise at a section of the wiring harness by the PCM. It got dark so I stopped looking but I think I am also going to open up harness and inspect it there.

Not sure how much this tells me but the short tester could not pick up a signal in this short portion of the harness.

 

After some research in the service manual I started following the asd circuit and found this damaged harness for the rear o2 sensor. The green and orange wire seems to have a bit of wire sticking out and the brown and blue wires are melted together. I have disconnected this but I still can't test. I am pretty certain this was the only problem and kinda surprised this car even drove for the while I had it driving. Do you guys think this would be the only problem?

 

"Do you guys think this would be the only problem ?"

NO

 

Lol I already ordered a big 7 wiring kit they just take long to ship so I wanted to rule out everything. I'm also wondering if the o2 sensor connected to that short is fried because it was new sadly.

 

Whats the solenoid by the battery, and that thing with the wires going in it on the firewall by the washer fluid res?