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Thread: 96 ZJ dying again! Reply to Thread
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  Topic Review (Newest First)
02-17-2019 04:45 PM
xtrattitude4u The Jeep's been running fine since I switched back to the old coil.

Big thanks to ZeeJay and Goldwing for the suggestions.

On a side note, the dirty dozen is an amazing thread, thanks for putting that together ZeeJay.
I didn't know about it until you mentioned it.
Need to search better I guess.

So my initial problem was the crank sensor, although it was a new MOPAR and only 2 yrs old.
Not sure why the original lasted 20 years and this one lasted 2.

It tested good every time I tested it, so there was no hint of any issue until I replaced it. The CEL never came on, even after cranking with no start.
Last time it failed, the PCM threw an ignition code once it was in crank no start.

The PCM was also on it's way out, so I'm glad I took care of that. I'm not sure it was causing any dying yet, but it probably was going to soon.

All the grounds are now pristine as well.

I created problem #2 by putting in a coil with pins that we're too small. So don't buy Delphi brand coils, because 2 of them had that problem.

With all the cranking we did the 1year old battery probably needs to be done now too. [emoji1787]

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02-10-2019 10:31 PM
xtrattitude4u Thanks for the suggestion ZeeJay!
I think I figured this out.

I took the connector apart and test fitted the sockets on the original coil and they held on great on the right pin, ok on the left.

I then took the new aftermarket coil out and the fit was horrible. Both sockets are so loose on the pins they basically just fall off.

So the pins on the new coil are slightly smaller in diameter than the original.

The left pin on the original coil was slightly loose so I ovaled the socket slightly to get a better fit.

Some more test drives are needed to be sure, but I think this is the final issue. If the coil gives me any trouble, I'll get a Mopar one. The only reason I replaced it was the resistance was lower than spec, but maybe that's not a problem.

Another lesson learned the hard way about aftermarket parts. [emoji57]

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02-08-2019 09:27 AM
ZeeJay1997 Oh yeah, it's easier if you have the coil removed when you fit check the sockets.
02-08-2019 09:04 AM
ZeeJay1997
Quote:
Originally Posted by xtrattitude4u View Post
The funny thing is, I can't get it to die by wiggling that connector. I also can't get it to start up again when I wiggle that connector during crank no start.
The socket makes contact with the pin with hairlike, spring loaded wires. Once they get weak and carboned, they are peculiar about passing current. While you have it apart, spray some contact cleaner inside the sockets and blow them out with compressed air.


You may have to replace the connector.
02-08-2019 08:54 AM
xtrattitude4u
Quote:
Originally Posted by ZeeJay1997 View Post
The two pin connector at the coil. Take note of which wire goes where. Slide the red tab out, open the connector, and remove the sockets and wires from the connector. Do a fit test on the pins, one at a time. They are probably loose. Use a small pair of pliers to VERY slightly elongate the bore of the socket. Easy does it. Fit test again. Repeat until the sockets have enough friction to hold themselves firmly.


Did this to mine about 100k ago and no more coil codes.
Thanks Zeejay.

I'll be doing this.
I swapped the coil again last night but it's still doing the same thing.

The funny thing is, I can't get it to die by wiggling that connector. I also can't get it to start up again when I wiggle that connector during crank no start.

It seems only tapping on the side of the coil will spring it back to life. I can't get it to die by tapping on it either, only get it to fire up and run for awhile after tapping on it.

I forced the guy at the parts store to tap on the coil I returned on their test bench. [emoji23]


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02-07-2019 10:38 PM
ZeeJay1997
Quote:
Originally Posted by xtrattitude4u View Post
So the brand new Delphi ignition coil I just purchased is bad.

The two pin connector at the coil. Take note of which wire goes where. Slide the red tab out, open the connector, and remove the sockets and wires from the connector. Do a fit test on the pins, one at a time. They are probably loose. Use a small pair of pliers to VERY slightly elongate the bore of the socket. Easy does it. Fit test again. Repeat until the sockets have enough friction to hold themselves firmly.


Did this to mine about 100k ago and no more coil codes.
02-07-2019 01:36 PM
xtrattitude4u Well it died again.
It started up once enough for us to park it, then was back to crank no start.

This time it threw a code:

P0351- ignition coil primary / secondary circuit.

I had my wife try to crank it while I wiggled the PCM connectors first, nothing. Grab the harness and shook it around, nothing. Wiggled the main ignition wire around, nothing.

Grabbed a screwdriver and gave the coil a good tap on the side, boom it started right up.

So the brand new Delphi ignition coil I just purchased is bad.

:Facepalm:



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02-06-2019 09:08 PM
xtrattitude4u There were still no codes stored in the PCM.
I followed the dirty dozen and cleaned the fuse box connections, alternator connections, and all the relay and fuse contacts, no dice.

Today I received a new Mopar crankshaft sensor so I installed it. Took her for a test drive for over an hour and there were no issues.

I'll need to give it more time to be sure, but it seems fixed. I tried viewing the 5v signal output of the original sensor with a oscilloscope but I couldn't get any clear reading.

While I was at it, I upgraded the batt ground cable and installed the military spec terminals.

The crank sensor was only 2 yrs old and was a Mopar. But the silicone was already separating from the lead wires, allowing moisture and who knows what into the sensor, likely shorting it out.

I may pull it out and cake the top in more silicone in attempt to make it last longer.

I guess they don't make them like they used to.







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02-02-2019 10:17 PM
xtrattitude4u Zeejay, thanks for making that, I am going through it right now. I use Tapatalk and it doesn't show the signature.

I feel I need to point out once more that I found wiggling the PCM connector was making the Jeep die.

I went after the problems I could identify first.

The coil tested out of range so I replaced it.
The dizzy had play and the cap/rotor we're both in dire need of replacement anyway, so I did that next.

Up to this point, the Jeep never acted up for me.
I just test drove it today and it died several times.

The surging before it died was strange, like someone was abrubtly tapping on the brakes.
I was able to get my spark plug tester on it while it was in crank no start condition and confirmed there was no spark while cranking.

The check engine light came on during the no crank but went away again.

Left my scan tool in the other car, will scan it and see if there's any clue there.

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02-02-2019 08:56 PM
ZeeJay1997
Quote:
Originally Posted by poriggity View Post
I want to say thank you for writing this up for us ZJ guys.

Your welcome. Good luck with the ZJ.
02-02-2019 08:46 PM
poriggity I want to say thank you for writing this up for us ZJ guys.. I haven't had any issues with mine yet, but you can bet I'll be referencing it at some point.. And I too am going to put it in my signature.. If for nothing else, to make it easier for ME to find when I need it

Scott

Quote:
Originally Posted by ZeeJay1997 View Post
LOL, I have no thunder... just when i eat dry beans.



Thanks, Maybe someone will read it.

I reckon it's the result of my ego that, when I find someone on here tearing into a PCM, I assume they have done all the simple and free things already. I suppose I should have dissected/ interpreted what had been posted in the thread.

However, through the the years, i have found only a handful of people who make a post and take the advise given. That's why I don't spend a lot of time on here anymore. People want immediate gratification.

Most people who are successful at the easy fix just take the info, do the repairs, and drive away without making a post.
02-02-2019 07:44 PM
ZeeJay1997
Quote:
Originally Posted by GOLDWING View Post
Sorry to steal your thunder ZeeJay,
LOL, I have no thunder... just when i eat dry beans.

Quote:
Originally Posted by GOLDWING View Post
P.S. I put a link to the dozen in my signature ZeeJay1997
Thanks, Maybe someone will read it.

I reckon it's the result of my ego that, when I find someone on here tearing into a PCM, I assume they have done all the simple and free things already. I suppose I should have dissected/ interpreted what had been posted in the thread.

However, through the the years, i have found only a handful of people who make a post and take the advise given. That's why I don't spend a lot of time on here anymore. People want immediate gratification.

Most people who are successful at the easy fix just take the info, do the repairs, and drive away without making a post.
02-02-2019 07:02 PM
GOLDWING
Quote:
Originally Posted by ZeeJay1997 View Post
SMH...

There was a reason I spent hours upon hours writing the dirty dozen.

You can lead a horse to water...
Sorry to steal your thunder ZeeJay, I have read the dirty dozen several times and appreciate the work involved in such a detailed thread. I also understand that the grounds were once not so high on the list.
When I see a thread like this one where 5 or 6 guys "know" the PCM is the culprit and others have solved it with the (CKP/ CPS/ IAC etc.) sensor and the OP does not know which way to go I always question electrical connections, focusing on the often ignored grounds and battery terminals.

GW

P.S. I put a link to the dozen in my signature ZeeJay1997
02-02-2019 05:55 PM
ZeeJay1997 SMH...

There was a reason I spent hours upon hours writing the dirty dozen.

You can lead a horse to water...
02-01-2019 06:28 AM
GOLDWING
Quote:
Originally Posted by xtrattitude4u View Post
Today I found the ground point underneath the coil. Took the studs and bracket off, cleaned with pb blaster and some corrosion cleaner. Then wire brushed the studs, bracket, terminal rings and and grounding nut. I found one of the rings was really concave, so pounded it flat and put it all back together.

It was nasty, corroded a bit and covered In grime.

Drove the Jeep home from 30 minutes away without even a hiccup.
I'm gonna redo the other 2 remaining grounds tomorrow.

I've ordered military spec battery terminals and a lug crimper. Gonna redo the terminals before taking it very far again.

That PCM ground does seem inadequate.
What is that like 16 gage wire?

I'd like to upgrade that too, but where is the other end? Do you have to splice into the small wire

Anyway, really appreciate all the advice.

I'm gonna have the best running Jeep on the road by the time this is done!

[emoji16]


Sent from my Pixel XL using Tapatalk
I am pleased that your ZJ no longer hates you.
I have given the same advice to quite a few forum members, and a few have followed it. Even if the grounds are not the main issue, cleaning them costs nothing but time and effort and will save a lot of money in parts that were replaced because of a symptom caused by a sensor/PCM not getting a proper ground.

GW
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