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 Post subject: CRD Liberty no crank issue (solved)
PostPosted: Thu Apr 27, 2023 12:24 pm 
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Joined: Thu Apr 27, 2023 10:53 am
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I just wanted to make a post on here incase anyone else is dealing with the same issue and give them my fix to try instead of spending weeks like i did to try and figure it out.

The start
I bought this diesel liberty off an older gentleman, that was unable to drive, for a very good price, it had issues, mainly being egr related, according to the codes, and a dirty/moldy interior. I did what any other diesel enthusiast would do with egr issues, and you know, got rid of them. Took a lot of searching around, and git it garage had removed a very helpful video, so i was a bit in the dark on what i was doing, but was able to find some pdf instructions online from an old kit by sasquatch (i believe i got my stuff through ID parts). I went through, got all the work done, went to start it, and got the big finger. It would crank for a second or two on the initial crank, then click like the battery was dead, or like I had a loose connection on the battery.

The Problem
The jeep would crank at max for 2 seconds, and not start, or it would click as if the battery was dead. Generally, i could let it sit a few minutes, it would crank once briefly, then click thereafter.

The jeep had sat for years before i got my hands on it, the guy helping the gentleman i bought it from had load tested the battery and said it was good after being charged up. I figured screw it, start fresh with a new battery. Went and got a battery popped it in, same issue, even when on the charger.

My solution

Grounding issue with PCM - Read below to see what I tried to narrow it down, and how you can test your issue easily to see if it fixes it (at very end).

Things I tried in order to narrow down my problem

First things first, i installed a new battery, i have chased similar issues on a jk that were eliminated after swapping in a new battery (story for a different time). I then decided to test voltages around the jeep. I was getting a good 12+ volts or so all over where it should be (i didnt verify at computer). I checked fuses, nothing broken, i swapped out relays, no help. I pulled the relay out of the starter and hotwired it with the key in the on position like i had seen on youtube, still wouldnt start, but it would crank over just fine. I then thought i may not be getting 3000+ psi to the fuel rail since I removed the fuel head to access the egr area. I bled the system multiple times, thought i might be getting air triggering something in the computer to not start. I plugged in my obd scanner that has sensor monitors, cranked it via the hotwire (as is was just getting a click from the key) and had seen i was getting adequate fuel pressure. I then began to wonder if my ignition switch/pushrod was causing an issue. I found a post http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=91675&start=20 on here that was very helpful in identifying if that was my issue, look at the comment by billybob. It wasn't my issue. I also wasn't having a skim or security issue, as the red light next to the fuel gauge was not staying lit. I was getting 12v to the starter relay when i would turn the ignition to start, signaling everything there was good. I did try running a jumper wire to the supposed ground location on the starter relay to see if I could start it (I must have done it wrong and shorted it, blew a fuse). I thought maybe my grounds were having issues. I checked behind the headlight, cleaned that one up, checked the firewall, still had the persistent issue. I was reading the forums on a particular guy down in Costa Rica that had to add a ground in on the starter relay (green and orange wire? in the relay box wiring?), and his pcm case in order to start his, and then he had transmission solenoid issues as well, but he got everything to work. After trying almost everything I could think of to try, testing everything instead of throwing parts at this, and wondering why I get myself in these situations, I put down my beer and said screw it, grabbed my jumper cables, hooked one end to the negative battery terminal, and the other end onto the case of the PCM. I went and gave it a hopeful twist of the key, and sure as doo doo, it cranked right up and started!! I removed the jumper cable and cranked on it, same issue persisted. I added it back, started right up. I would also like to note that I could crank in park and neutral, i have had plenty of jeeps with NSS issues, this did not appear to have it, although the gear shift does move out of park without having to have your foot on the brake. I couldn't believe I solved my problem, then I remembered something I did before this whole mess even started.

What I believe caused my issue
Before I even got started working on my egr, I removed the battery, while removing the positive side I wasn't paying attention to where my ratchet was and arced it on what I thought was the fender (I remember this because it made me jump and also made me think how dumb I was that let that happen.) Well, the fender and PCM are very very close to each other, and well within reach of my ratchet handle. I am almost 100% sure that I smacked the pcm case and shorted it directly to the battery when I was removing the battery cable, which, with the smaller gauged wiring that it uses and the sensitive internal components, I would assume caused some electrical gremlin issues that were nearly unidentifiable.

Physical fix
After identifying this issue, I took one of the mounting nuts off of the computer near the top, added a grounding wire behind the nut, directly in contact with the pcm, and ran the grounding wire to the ground stud on the firewall near the fuel filter. I have not had the cranking/no start issue since. Using the jumper cable method to provide a ground directly to the PCM case from the battery is an easy way to rule out if the no start no crank or short crank issue is due to grounding problems with PCM.

Moral of the story, grounds are important, pay attention to wires while you're working on something to be careful not to pinch, pull, or short them out. I just had to trace an issue on a motor swap in an xj cherokee to the cam position sensor within the distributor, wire got tugged on a bit during motor removal (i remember because i had to go get it untangled). It was an intermittent issue because you couldn't see that the wire had an issue unless you wiggled it.

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2006 Liberty CRD
2015 Grand Cherokee SRT
2007 JKUR on 40s with RIPP Supercharger
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 Post subject: Re: CRD Liberty no crank issue (solved)
PostPosted: Thu Apr 27, 2023 3:33 pm 
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Very glad you figured it out! :BANANA:
Wish you had told us about shorting out the ECM to the positive battery terminal up front, advice would have been quite different. :shock: :banghead:
You are very lucky indeed! Count your blessings; there have been a couple of others on this forum that have done the same thing and it fried the ECM and they had to replace it. This gets very expensive with purchasing an ECM and getting it all programed with the correct VIN number, mileage, security code, etc... $$$$

As a precaution to this, I made a cover out of some rubber insulation tape and covered my ECM to protect it from anything accidently coming in contact with it.

Image

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 Post subject: Re: CRD Liberty no crank issue (solved)
PostPosted: Mon May 01, 2023 11:54 pm 
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Joined: Sat Apr 15, 2017 3:48 am
Posts: 462
Location: White River in the Bush South Africa
Glad you fixed your "ECM" grounding...."PCM" is for Gassers! :wink:

When my 2002 Export 2.5 CRD was relatively new I had some issue with starting and fixed it by grounding the Metal case of the ECM to chassis....so long ago I had forgotten about it! :wink:

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