TXVikingXJ

Hey y'all, I've had my 99 XJ 4.0L automatic for about 6 months and then it started acting up about 4 weeks ago. Wouldn't accelerate correctly, not shifting right. Then it got worse and started dying sometimes. When it would die, I would have to wait until the next morning until it would start again. So yesterday I replaced the TPS thinking that had to be at least part of my problem. Got it replaced after hours of struggling with a stripped torx head, test drove it and it was better than before, but I still wasn't getting the acceleration it had before it started messing up. So I took it to the mechanic shop I worked at last summer and me and the owner started taking a look, and we found the 3 wire connector to the coil had wires showing and they were all corroded and melted together, so he started wiggling on them and as he moved them, you could here the jeep go from running fine to dying. As he was wiggling them with the key on but the engine off, you could here the ASD relay popping open and closed as he wiggled them. So I cleaned it all up and wrapped them nicely and plugged it back in and now the ASD relay is stuck with no power, so it will crank and crank and crank but no fuel pressure, no ASD, no PCM, no spark, etc. With the key on i'm now getting no voltage to the fuel rail, but my battery and ppm grounds are getting 7-8 volts each for some reason. So I'm thinking somewhere in my harness I have a short to power that's messing everything up. I have tested the Crakshaft position sensor like directed in other threads and it is good. Before we started wiggling wires, I had great fuel pressure. Not sure if it helps, but when you supply power to the grounds that are getting voltage, it turns the fan on? So I spent all of yesterday unwrapping my harness starting at the end with the grounds and coil connection looking for my issue with a test light, and when we get close to it and start moving it just right the light flickers. But I just cannot for the life of me track it down, so I am just shooting in the dark here in case someone has some golden piece of advice that could help me out. Also, my gauges are dead with the key on, no fuel and voltage. I know this is symptomatic of CPS, but we have tested it thoroughly. Also, the code reader can't connect to the PCM as it sits now with this issue. Any help or advice is appreciated very much. Thanks y'all!

TXVikingXJ

Also, I have checked all relays and fuses both in the kick panel and the engine bay. I have narrowed my issue down to the segment of the wiring harness that plugs into the PCM closest to the firewall.

Turbo X_J

Start with checking the resistance of the battery cables, go from there.

BlueRidgeMark

Please provide more detail on how you "cleaned it all up".

TXVikingXJ

I separated the wires, brushed the gunk off and wrapped each individually very neatly.

Now at this point I've spent the day pulling the harness and looking for any other issues and found none. I'm getting voltage in places that shouldn't have voltage and when I ground them out, I'm getting things like my AC fan turning on. At this point I have no clue what's going on. I've checked all my ground wires. But for whatever reason I'm not getting through from the PCM to the ASD. I'm wondering at this point if it's possible that those funked up shorted wires when jiggled around didn't for some reason blow something in the PCM.

TXVikingXJ

Here's what that connector looked like when I found it.

BlueRidgeMark

Electrical tape can come undone. I would not trust that repair at all. Not even if I did it.

I suggest you remove that connector completely. Strip the wires back until you get to good wires, and then splice in a new connector.


Also, see my sig, #1.

jordan96xj

There is a lot to chew on in this post. But let's start with something basic, that connector you pictured needs to be replaced. Not repaired. Start there. That is a bad failure of a connector, and you could easily be providing some voltage to ground, or worse, back to the PCM with a connector in that bad of shape.

Is that the 3-wire connector to the camshaft position sensor?

TXVikingXJ

Thanks for the reply.

I stripped it back until I found good wires and wrapped from there. I removed the entire engine harness, checked every connection and cleaned them all up and tested for ground and voltage in every single connector. Everything checked out with the engine harness isolated from the rest of the wiring harness. I intend to do more than just leave it with electrical tape, but for now, as far as I can tell, that particular connector isn't causing my problems at this point.

I've removed every ground i'm aware of and cleaned them up, and put them back and checked them for voltage. All of them are grounded well except for whatever reason as soon as I plug the engine harness back into the PCM, I get roughly 7-8 volts running through the two grounds on that harness.

TXVikingXJ

Yes it is.

BlueRidgeMark

That wire itself is not trustworthy, no matter how well it's wrapped.

That's a weird failure, too. Looks like acid damage. Odd, and makes me wonder what else might be in bad shape.

TXVikingXJ

Yeah, from what I can tell there was a bad valve cover leak at some point, because there is a nice new valve cover gasket there and a mess of oil down the side of the block. Looked to me like hot oil had been spilled all over it. Can't be sure though. I found one other connector that was rough and I spliced out the bad portion. In your opinion is it possible my pcm is bad and giving me these issues? I just can't think of what else it could be at this point. I'm not a pro by any means but I'm up to about 22 hours of labor into this issue and I've never felt so overwhelmed. Never been stumped like this by a vehicle.

jordan96xj

I normally do not suggest that the PCM is the issue (because too many people jump right to that). But when ever a 3-wire sensor connector has been as thoroughly destroyed as what you pictured, then yes, there is a possibility that the PCM was effected. Basically exposed wires, touching/arcing to each other at the connector, and at least one of the wires has a direct path back to the PCM.

So yes, it is possible that the PCM got more voltage back on what of those wires than it should have, and that could cause problems. Whether or not that is actually what the trouble is, I don't know.

BlueRidgeMark

I agree with Jordan, but....

I wouldn't go there until that connector is replaced, all the way back to wherever there is sound wire.


That damage was not caused by an oil leak.

TXVikingXJ

Alright y'all thanks for the advice. I'm gonna get back on it first thing tomorrow and deal with that connector. If that doesn't change anything, I've got an offloading buddy thats got a 99 that he's willing to lend me the PCM out of to see if it changes anything. Thanks again for y'alls advice, I really appreciate it. I'm definitely a bit out of my depth with this.