My car alarm goes off at random: in the parking lot, while driving, etc. Fortunately it will turn off when I push the unlock and lock buttons on the remote, or use the key in the door lock. The Chrysler service manual says to test the door ajar sensors, rear hatch ajar sensor, the hood ajar sensor, the tow away sensor, the SKREEM system (behind the instrument panel), and the security / power lock system (in the trunk).

I have read many suggestions about changing the car battery and the remote batteries. I changed the remote batteries and the car battery is fairly new. I do not have the DTC III diagnostic tool since it costs thousands to purchase. The service manual doesn't seem to indicate a specified voltage that I should test for. Does anyone know how to isolate the problem and fix it without just replacing random parts? Has anyone out there had similar issues and found resolution?

 

there's plenty of reading on the topic.. my alarm went off while driving and a replacement of the siren fixed that particular issue, but it does still go off at random unless its unlocked. I suspect the module in the trunk but haven't gotten around to digging through the foam.

 

The remote batteries have nothing to do with the alarm. Not many people here have the expensive diagnostic tool. Most have the approx. $100 or so OBD 2 code reader. It works and is cheap enough and can be had for less than $100 with lesser features (maybe).
I would look at the trunk pump/security module for water damage to start with as it seems to be lock related.

 

check the battery terminals as they may be loose or corroded, I dealt with this last week on my ML

 

I soldered some bad joints on the RCM today and it seems to have fixed another problem with the secondary air injection code I was getting. I noticed my glove box had trouble staying closed because the receiving end for the latch was lose. I tightened it with a Torx screwdriver. I am curious if the glove box sensor was triggering the alarm

I don't know if the security system connects to the RCM or a different control module. If it connects to the RCM I am curious to see if it fixed the alarm issue.

 

Battery terminals are good. I checked them today.

 

If the repairs to my RCM don't stop the alarm I'll dig through the trunk and check the security / power lock module in there. Thanks for the suggestion.

 

Repairing the RCM seems to have stopped the symptom of the car alarm going off on its own.

 

I have the same problem and have run codes to no avail. It's become so sporatic that I just check to make sure no one is stealing it when I hear it, otherwise... Oddly enough, it seems to happen only when it's locked and either first thing in the morning or in the middle of the night (weather conditions??). I haven't found a pattern yet-but everything I'm finding points to something to do with the battery. No worries. It's now just a simple reminder that my Xfire is still there.

 

Both of you should check if there is water leaking into the hatch. I believe that's a common cause of the alarm acting up also, but I may be mistaken.

 

Common cause is the siren battery leaking and corroding the circuitry inside the alarm.
Two adventurous people took the alarm apart, cleaned it up, added new batteries and reinstalled the alarm.
Click here to read how you could save $160.

Other times it is the car battery failing, bad connections in the sensors in the locks and latches among others I have forgot.

 

After fixing some other weird electrical issues I'm still having this problem. The siren doesn't always sound, or goes off sounding half-assed. I think the siren is dying and may be tripping the alarm.

 

I had the trunk half ripped out testing for other problems. It's bone dry. Fortunately since I live in Phoenix I'm not worried about water damage and rust. I have to worry about heat damage (keeping the body clean and waxed, dry rot, cracked dash, cracked leather, etc.).

 

The half-assed sound is the 'cricket on crack' syndrome and is definitely the fault of the siren. So repair (not for the faint of heart) or replace with the new $160 siren that chirps when you lock or unlock the car.

 

Hi Guys,

After my experience with the alarm going off randomly I agree with what 180 is saying. My theory though is that replacing the main vehicle battery might just delay the return of the siren tripping.
I think there might be two failures of the siren module.
(1)The batteries inside the siren seem to go through a charge / discharge cycle automatically I think its possible that when the batteries start to fail in the siren it pulls more amps than the alarm is expecting and therefore triggers itself ie only when its armed.
(2) a short in the charging circuit that can occur anytime leading to it sounding whilst driving.

Which fault you get at any point depends on which bit of the circuit board is being eaten by the battery acid at the time!

A new vehicle battery MAY just provide enough amps so the drain caused by a failing alarm battery is not detected but it wont help the sounding whilst driving faults.

Get the siren taken out and either replace it with another one from MB ( in the UK MB say they always have stocks because they keep failing) or rip it apart and hope its not too badly corroded and can be "repaired"


BBlanchard, my siren sometimes didnt work then suddenly started working and wouldnt stop!

Matt

 

Check the glove box switch. unplug it and see what happens. OR go to the dealer and have them scan the car it will, unlike an obdII scanner tell you exactly which input is being triggered. I chased the same thing for over a year and it turned out to be a 20.00 switch for the glove box that hade a faulty relay in the switch.

 

I unplugged my siren several years ago. Everything else still works, no codes, no alarm in the middle of the night. Took about ten minutes and cost nothing. It's not like anyone responds to the sirens anymore anyway. Other than to throw something at your car or leave you a nasty note.

Zorro

 

Alarm going off on its own! Interior light flickers / unlocking randomly if driving!!
Still trying to find cricket on crack. My siren has been weak for years no on my 04. I kind of liked not having the noise, but it seems to have progressed leaving me stranded at work yesterday. Yesterday the fob wouldn't open the car. Opened with the key and the alarm lights started. It didn't stop with the fob or inserting the key. When it stopped I started the car but it quickly died. Then it would not turn the starter at all. Saw in another post to remove fuse #9 to disable the domelight, horn and alarm. The light went off, but the horn and the alarm both still worked. Replaced the fob batteries, no help. Had no tools at work so I called a tow truck. He tried to jump it to no avail. At home I found a post and decided t follow the suggestion to take the 10mm to the negative and disconnected and reconnected the battery. I could not start now since the battery was low. Put on the charger for a few minutes and it started .Drove 38 mi to work where it restarted fine. Did not lock the car. 10 hours later it started and drove home fine. I am going to try replacing the siren next. So glad all of you are there to help figure out these issues. The local dealer quoted $8-900 to replace the SKREEM but it seems the siren is the problem from what I have read here in the forum. allmoparparts.com/oemparts/5124443AB has it for $144 plus shipping. I'll call around town tomorow and see if someone can get it sooner of without shipping costs. We'll see.IF the doors work with thsiren disconnected, I'll stop there

 

Starting at least seven threads on your current problems has got to be some kind of record. Who is going to read seven threads to see what has been suggested so far? Not me. Sorry.

 

replaced the battery in the key fob. Seems to have fixed the problem