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-   -   New PCM, now won't start. (http://www.jeepforum.com/forum/f13/new-pcm-now-wont-start-1782345/)

Nolvck 11-11-2013 11:03 PM

New PCM, now won't start.
 
Hello again, thanks for looking. Hoping someone is able to help me diagnose my headache... I had a weird speed sensor issue and determined my PCM was trash. Ordered a new one (programmed to my vin) and got it in today. With more excitement than a toddler on Christmas, I ran to my garage and installed what I thought was going to fix my rig. She started up and ran great for about a minute then shut off. With fear in my eyes, I turned the key and tried to start her again... but no dice. Motor turns over and wants to start but falls short. I replaced battery and terminals a few days ago, and didn't even consider them to be a problem, until I tried starting her again and my check gauges light came on. My battery gauge sits at zero and my battery completely drained in a matter of minutes. Starting to think the alternator took a crap but not sure why it ran fine before with a **** PCM and bad battery and term. Fuses and everything tested fine.

So here's the quick play-by-play...
-NEW PCM
-started then died.
- cranks but won't start.
-check gauges light.
-battery gauge at 0
-new battery and terminals
-NO CEL

JasonStebbins 11-11-2013 11:42 PM

]How did you determine the PCM was bad in the first place? Have you had the charging system tested? Is the current PCM new/used/remanufactured? Where did you get it? The voltage regulator is part of the PCM on these models. Does your Jeep have a security system? If you got a PCM from a ZJ without one, it will shut down automatically from the fail safe.

Check the wiring for the oxygen sensors, if they are exposed and touching something it can fry the PCM.

Have you ruled out everything else such as the CPS and fuel pump?

Pugulis 11-12-2013 01:57 AM

Have you trie putting the old PCM back in? You could have easily gotten a defective PCM. Also, try disconnecting the map sensor and starting it.

Nolvck 11-12-2013 02:51 AM

The old PCM had multiple solders busted. It was running rough and stalling pulled PCM and opened it up. Bought a refurb from "auto computers" online. My jeep does have a factory alarm that hasn't worked in over a year. I was thinking the CPS but was curious as to why this symptom would drain a new battery, made me think possible alt.

Oldfrog 11-12-2013 08:36 AM

Quote:

Originally Posted by Nolvck (Post 17634249)
The old PCM had multiple solders busted. It was running rough and stalling pulled PCM and opened it up. Bought a refurb from "auto computers" online. My jeep does have a factory alarm that hasn't worked in over a year. I was thinking the CPS but was curious as to why this symptom would drain a new battery, made me think possible alt.


The bold text is your problem. Both of those outfits in Florida are....how shall I say it........crooks?

JasonStebbins 11-12-2013 12:38 PM

Quote:

Originally Posted by Oldfrog (Post 17638633)
The bold text is your problem. Both of those outfits in Florida are....how shall I say it........crooks?

Yep. I've only read negative reviews about PCM's from Florida companies. You should repair your original PCM or else buy a Cardone brand. Here's a write up on how to do so.

http://www.jeepforum.com/forum/f13/9...tures-1303589/

The battery drain is probably from the faulty PCM. But I would get the charging system tested regardless.


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