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Is

Is there a way to tell or to bypass the security system?
Usually, when you open the door, the alarm goes off, the headlights flash, and the gauges will flicker. It will allow the jeep to start but will kill the engine after a second or two.

Turn the key in the drivers' side door lock and unlock. If the key cylinder sensor switches are bad on the driver's side then do the same on the passenger side. You can tell if it disengaged when the courtesy lights turn on when you unlock the door from a locked position.

This will disengage the security system. Usually, the Key FOB will disarm, but I have had them not work before. The locking and unlocking of the driver's or passenger's side door(while closed) will disarm the security system. (also in the PCM/ECM)

Sounds stupid, but if you don't have enough battery left when the alarm goes off: the horns don't sound nor do the lights flicker, but you will hear the alarm relays clicking in the fuse box area.

I am leaning towards a bad PCM. You can find one at a pick n pull for less than 180.

What did the former owner say about the car's apparent issues?

a running $260 ZJ is still really cheap..
 

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Discussion Starter #26
Usually, when you open the door, the alarm goes off, the headlights flash, and the gauges will flicker. It will allow the jeep to start but will kill the engine after a second or two.

Turn the key in the drivers' side door lock and unlock. If the key cylinder sensor switches are bad on the driver's side then do the same on the passenger side. You can tell if it disengaged when the courtesy lights turn on when you unlock the door from a locked position.

This will disengage the security system. Usually, the Key FOB will disarm, but I have had them not work before. The locking and unlocking of the driver's or passenger's side door(while closed) will disarm the security system. (also in the PCM/ECM)

Sounds stupid, but if you don't have enough battery left when the alarm goes off: the horns don't sound nor do the lights flicker, but you will hear the alarm relays clicking in the fuse box area.

I am leaning towards a bad PCM. You can find one at a pick n pull for less than 180.

What did the former owner say about the car's apparent issues?

a running $260 ZJ is still really cheap..
He just said it needed a crank sensor. She’s rough and I’d hate to put that much money into it and not be able to get that back out of it. At this point I’m about to start parting it out lol
 

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I had the capacitors go bad in my ecm on my zj. Leave the key in the on pos for like 10 mins then start it. Do not turn the key off before you try to start it

Sent from my Z982 using Tapatalk
 

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Discussion Starter #28
Changed out the ecm and still nothing, really lost on it now. There’s no horn but today I noticed it was making some strange noise inside the dash area and the red light on the drivers side dash by the windshield was on. What is that light? Could it be the security system not letting it start
 

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I installed a remote start in my buddies 98 grand and it would start and run for 8 seconds then shut off. took me a month to figure out the security was not programmed right. Once I finally got the bypass module programmed it worked great. So, my only experience with the security would let it start but then shut it off. I never had a no start issue. But I think if that red lite is on, then the ecm considers the security armed, and will probably prevent it from stating.
 

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I looked at the no start diags in my alldata and one test is to check the alarm system. you need a factory service tool (DRB) in order to be able to do this. another one says you need at least 44psi fuel pressure. and the fuel pressure regulator is in the tank.
File this under FWIW, guys have been having good luck using an old Snap-on MT2500 scanner with the Jeep cartridge to read the engine and transmission systems. I have a snap-on mt2500. I will check it our tomorrow and see what I have. I couldn't find anything about the alarm though, Sorry.
 

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Changed out the ecm and still nothing, really lost on it now. There’s no horn but today I noticed it was making some strange noise inside the dash area and the red light on the drivers side dash by the windshield was on. What is that light? Could it be the security system not letting it start
Was the strange noise a rhythmic clicking down by the passenger kick panel in the footwell? The sound of a couple of relays clicking on and off... the headlamps, the interior dash lights, and the horn relays I believe just a few of which ones flash on and off when the alarm goes off. I know I said that before but it is important. If the security is going off, then you know what is causing it. If the security is the issue then there are several sensors and switches throughout the car that need to be checked for functionality.

Yes the red light on top of the dash in front of the driver is the security arming light. When you lock the doors, it will flash once every few seconds after the alarm has armed.

If it is the security that is keeping you from starting it, it will allow it to start but will kill it just before it chugs to life.


The horn not work has me wondering if there could be a clock spring issue? Anyone else knows if that could cause a no start issue?
 

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File this under FWIW, guys have been having good luck using an old Snap-on MT2500 scanner with the Jeep cartridge to read the engine and transmission systems. I have a snap-on mt2500. I will check it our tomorrow and see what I have. I couldn't find anything about the alarm though, Sorry.
Those might be able to work with the security system, and they definitely can do FOB programming, bleed the ABS pump, and can actually read the transmission module for fault codes. I have been looking into buying a Chrysler DRB III tool if I can ever find one cheap enough. All I have found were the $3,000 variety. :LOL:

The Snap On MT2500's are a solid substitute for the DRB III tools but do not do EVERYTHING that the DRB III tools can do. However, the do have a better price point at about $250.. not saying you should go and buy one but maybe find a shop that has one and maybe a six pack of beer might be able to get someone to hook it up to the jeep and help tell you what is going on.
 

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Man i hope you figure this out and get this thing running! I’m no help here, never had to deal with this sort of issue, I’m just here to learn - I love a good troubleshooting thread.
 
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