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Unread 03-19-2014, 02:22 PM   #1
ryanf77
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PCM Issue - Security

Hello Again! I traced a No Start Issue back to the PCM on My 1996 Grand Cherokee 4.0 - Got a Used PCM on Ebay, plugged it in, the Jeep started right up, ran for 1 second then died! It keeps on doing this. So I contacted the seller of the PCM and he says that the PCM He sent Me was for a Jeep with Security and Mine does not have Security. Here's My Question... Is there a work around where I can make this PCM work without taking it to the Dealer and having it re-programmed? Thanks in Advance...

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Unread 03-19-2014, 05:18 PM   #2
coralman
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I think once the security option is activated in the pcm it can't be deactivated.
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Unread 03-19-2014, 05:57 PM   #3
WJon35s
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Check out the linked post it might work for you.
http://www.jeepforum.com/forum/f13/9...isable-521935/
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Unread 03-19-2014, 06:23 PM   #4
ZeeJay1997
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the post you see about grounding a wire to deactivate are for 93-95 zjs. the 96-98 has the security module in the bcm. no way to fool it. if the pcm no start feature has been armed by a security module, it must be disarmed by a security module.
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Unread 03-19-2014, 09:28 PM   #5
ryanf77
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Thanks for the Responses Guys... I'm going to Return the PCM I got with the Security Feature and then Open Up My old on to see if I can fix it (Watched some YouTube Videos on Repairing 'em). If that doesn't work there's an ebay company in Florida that will sell Me a Re-Man PCM that is programmed to My VIN for $170.00 delivered...
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Unread 03-20-2014, 03:48 AM   #6
coralman
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Zee, I must have something confused. I thought meangreen said that security was activated in the pcm and that it in turn would make the bcm security enabled. Do I have it wrong? OP ..be careful of the pcms you are talking about. Some have had a greater occurance of problems with them. Cardone units seem to have had a better track record but they cost more.
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Unread 03-20-2014, 06:50 PM   #7
ZeeJay1997
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i might have it wrong coralman. but this is the way the way someone explained it and/or my understanding of it.

every pcm of a particular part number is born the same. the all have an engine no start security feature in the firmware waiting to be enabled by a VTSS.. if the vehicle it is installed in doesn't have VTSS, the feature never gets enabled. You can use it in any compatible vehicle, VTSS or not.

once it is installed with a VTSS, the no start feature is enabled by the security system after 20 engine starts. from that point forward, it must have a CCD input from the security module to arm and disarm the no start feature. the only way to disable the feature is to reprogram the PCM on the sci bus. it must be installed in a compatible vehicle with security.

the difference between 1st generation and second generation zjs is that the gen1s have a separate security module that sends a security discrete to enable and disable (not arm and disarm) the no start. this is why you can get a first gen running and remove the security module and never have to worry with it again.

someone will probably trump this with factual info rather than conjecture, but I welcome it.
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Unread 03-20-2014, 07:47 PM   #8
coralman
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Thanks for the info Zee! The reason I was asking is I seem to recall a menu on the DRB where I could actually go in and enable the security features. I have hesitated trying it until I get around to installing the cylinder switches because I think the net effect would be a vehicle that didn't start. Also, while there was a menu for "enable" there was no option for disable. Hence my thing about not being able to wipe the system. When and if I get around to doing it,if it boogers stuff up I have several non alarmed BCM PCM combos non alarmed that I have aquired over the years.

The OP did bring an important note about buying used pcms. Ebay sellers sometimes sell the pcms not knowing if they are alarmed or not. Always ask. As far as I understood the VTSS is present in all gen2 but will not go into effect unless the conditions you said are met. But I think you can enable that function using a DRB. The more I learn the more questions I have.
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Unread 03-20-2014, 08:09 PM   #9
ZeeJay1997
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if i'm reading correct info, it can be enabled by advancing the engine start count over the CCD bus

to disable, it must be reflashed over the SCI bus.
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Unread 03-21-2014, 11:22 AM   #10
ZeeJay1997
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after further review, the scanner does all the communication on the sci bus.
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Unread 04-07-2014, 09:38 AM   #11
ryanf77
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OK Guys... More Issues Now! I got a Reman PCM on ebay from a Company in Florida. Installed it and the Jeep Ran Great! Went Wheeling for a couple hours in it and made a couple runs to the Hardware Store in it. Fired it up yesterday to take it down to My Garage (100 Ft Away). Turned it off. Checked the Bolts on My Recent Lift Kit Install. Went to re-start it and it just cranks and cranks - No Start Again. Checked for Spark and Nuthin. Removed the New/Reman PCM, Pulled it apart and it's burned up! Worse than My Stock one was. Any ideas what to do now? What could be burning it up? Here's pictures of the stock one (Less Burnt) and the Reman Unit (More Burnt).
photo-1a.jpg   photo-2a.jpg  
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Unread 04-07-2014, 10:23 AM   #12
jeepjeepster
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Is it actually burnt up or is that just the crap they put over the board turning brown?

Don't those PCM's have a warranty?

Whats a VTSS? So if the 96-98 zj's don't have a security module what controls the security? Is it all integrated in the PCM?
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Unread 04-07-2014, 10:36 AM   #13
ryanf77
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Quote:
Originally Posted by jeepjeepster View Post
Is it actually burnt up or is that just the crap they put over the board turning brown?

Don't those PCM's have a warranty?

Whats a VTSS? So if the 96-98 zj's don't have a security module what controls the security? Is it all integrated in the PCM?

I believe the "Goo" over the Circuitry is turning Brown when it Burns Up/Gets Hot. Guess I could be wrong about this.

It had a Warranty until I decided to Open it up! My worry is - Why is it going out. First My Stock one and now a Reman Unit...

Can't answer Your 3rd question!
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Unread 04-07-2014, 10:40 AM   #14
ryanf77
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I failed to mention in the Original Post that when the Stock PCM Failed we had been out Taking the Jeep through some Mud Puddles on a Rainy Day. I then went to a Street that Slightly Floods and Proceeded to go down the street at about 35mph to Clean off all the Mud! Almost immediately upon hitting the water everything shut down... That was the Stock PCM. Now I replaced it with the Reman Unit and it Failed pretty quickly after normal driving. So, I'm thinking that more than likely something happened when We went through the water that is now causing a Short or Power Surge or something back to the PCM...???
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Unread 04-07-2014, 11:12 AM   #15
jeepjeepster
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Checked the O2 sensors? Never heard anyone say for certain, but Ive read they can take the PCM out is they are sorted out.
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