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Discussion Starter · #1 ·
2001 Jeep Grand Cherokee Limited, 4.7L. I have read many threads on here about the PCM, but I wanted to ask before installing a different PCM. I replaced the battery about 2 weeks ago. Jeep ran fine. Then, when trying to leave Walmart, it would not start, not firing. I checked codes and P0601 was the only one. Erased it, and Towed it home. Later, unhooked battery and got numbers off the PCM. Hooked up battery and tried to start it, no start. Checked codes again, and it had Code P0340. Erased code, then tried to start again. No Start, checked codes again, and got P0601, and P0340. My question is, should I go ahead and replace the PCM or should I try to replace the Camshaft Position Sensor first, and see if the Jeep starts? Thank you!
 

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My $.02:
The CAM Sensor is much cheaper and an easy R & R.
Ensure you use the MOPAR brand.
 

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I would also suggest you look at the CMP -
Do you have a SCANNER the key on off may be lacking in code reading ability.

DO NOT buy a PCM - first contact waterluvr a forum member about PCM replacement.
 

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Discussion Starter · #4 · (Edited)
I would also suggest you look at the CMP -
Do you have a SCANNER the key on off may be lacking in code reading ability.

DO NOT buy a PCM - first contact waterluvr a forum member about PCM replacement.
OK, CMP is Camshaft sensor and it looks like its easy to change by removing the battery and battery tray. I do have a cheap scanner that I use to hook up to OBDii connector to read the codes. I did not do the key trick to read the codes. I have sent a message to Waterluvr.
 

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Discussion Starter · #7 ·
P0601 is a death sentence for any ecu, you can load up a parts cannon full of sensors and fire away but I promise you that pcm will leave you on a tow truck home sooner later.
OK, I'll try to find a PCM in a junkyard and see if you can re-program it and program it to my VIN for me. My PCM number is P56044690AH. Does anyone have a used PCM with this number?
 

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OK, I'll try to find a PCM in a junkyard and see if you can re-program it and program it to my VIN for me. My PCM number is P56044690AH. Does anyone have a used PCM with this number?
Any pcm with part # P56044690 (AE~AJ) will work, last two letters are software update revisions and I install the latest download version available from Chrysler Tech when I re~flash a module.
 

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Any pcm with part # P56044690 (AE~AJ) will work, last two letters are software update revisions and I install the latest download version available from Chrysler Tech when I re~flash a module.
Don't know if this will help you but most of the time it is one of the two diodes in the PCM that goes bad. It is a really easy fix to just replace both diodes. I think I spent 10 bucks off eBay for the diodes and replaced them myself with a soldering gun. Pretty cheap and easy!!!
 

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Discussion Starter · #10 ·
Any pcm with part # P56044690 (AE~AJ) will work, last two letters are software update revisions and I install the latest download version available from Chrysler Tech when I re~flash a module.
How about this PCM with AD as the last 2 letters? instead of the (AE-AJ) as you mentioned above ? ID#56044690AD,,CONFIRMED--OFF RUNNING VEHICLE--ON SHELF. Located in Erhard, MN. Can you program this 1 to work in place of my P56044690AH original?
 

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How about this PCM with AD as the last 2 letters? instead of the (AE-AJ) as you mentioned above ? ID#56044690AD,,CONFIRMED--OFF RUNNING VEHICLE--ON SHELF. Located in Erhard, MN. Can you program this 1 to work in place of my P56044690AH original?
Send me an email with any further questions please, it could be days or never before I see thread replies.

I'll need your vin to pull a build sheet, yes it will work.
 

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Discussion Starter · #12 ·
I purchased a used PCM from car-part.com and Waterluvr reprogrammed the PCM for me. I installed the used PCM and the Jeep fired up and is running great! No more P0601 code and no other codes at all. Thank you Waterluvr!
 

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I purchased a used PCM from car-part.com and Waterluvr reprogrammed the PCM for me. I installed the used PCM and the Jeep fired up and is running great! No more P0601 code and no other codes at all. Thank you Waterluvr!
That was a really nice pcm you got from them cleanest one I think I've seen yet! I've added some new hardware and software to my programming workbench that not only allows for flashing these properly but I can test and graph most of the critical functions like sensor output voltages etc. while it's all hooked up.

That's easy enough to do if you have the vehicle there on hand with a shop level programming tool but pretty challenging to do on a bench top I stripped wiring harnesses out of all the applicable Jeep models and built bench top programming and test harnesses that can mimic almost all the relative operating functions now.

Thanks for the feedback, glad to hear it's back on the road again!
 
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