Chrysler Repair: 2000 Sebring Alarm Goes Off, fuse box, car doors

Question
Hi Roland,
I have a 2000 sebring convertible and every time we turn the car on the alarm goes off.
I tried the on-off-on-off-on key sequence that I found in one of your other replies,hoping I could get some sort of code, but I guess it doesn't work the same on this model.
If we wait 18 minutes, the alarm resets and the lights stop blinking. I pulled the fuse from the horn so it's drivable. Also, the door locks don't respond to the switch's on either side. But the locks do still lock down when you hit about 18 miles per hour.
Any ideas would be greatly appreciated.

Thanks,
Ray

Answer
Hi Ray,
A couple of caveats: I don't have a security system on my '89 Chrysler and really haven't worked on them personally and I only have the '96 Cirrus shop manual which is a contemporary design to the Sebring but there could be some difference between the vehicles. From what you describe it would seem that the system is arming when you shut the car doors but I wasn't sure if you do that or not and if so how you are doing it. On the assumption that you are arming the system, then it sounds like two things are going wrong when you open the door to the car while it is in the armed condition. First, the system is not disarming via the door key and second the system is not detecting that you opened the door so it doesn't alarm at that point but rather when you turn the ignition to "on" which is another trigger point.
This is suggesting to me, along with the fact that the keys don't cause the power door locks to either lock or unlock that the voltage to the arm/disarm switches in both doors is not present (which also suggests that the system is being armed otherwise, perhaps with a remote?) The power to make the power door lock switches and arm/disarm function is a fuse in the fuse box under the dash which is 10 amps (#5 in the Cirrus but check for labels in your Sebring). So find and check that fuse to see if you can get the power locks running again. That may solve the problem. But the other fact that is a bit of a mystery is why the alarm doesn't go off when you open the door (assuming indeed that the system is still armed). That could happen if the door ajar push button switch in the door frame (either in the jamb or at the rear edge, I'm not sure which) is not grounded well (which is what is required to sense that door is ajar as well as 'open' for alarm purposes). Does your car have a door ajar warning light on the dash and does it work? If so, then I'm wrong about this. If it doesn't then the ajar switch body is probably loose and not making good electrical contact with the metal of door frame where it is attached. So check/tighten that.
The other possibiliy is that the body control module wherein the security system and power locks system resides has some shorts or opens in and around its plugs. The module is located in or around the fuse block under the dash and it has about 4 multipin plugs (10,14,20, and 22-pins). With the convertible body there is more opportunity for water to leak in and get into the pins and sockets of those plugs. So I would suggest that you also use a spray can of electronic contact cleaner (from an electronics store) to remove any crud or corrosion from around those pins and sockets, removing each plug and spraying its pins and sockets. That often solves a gremlin-like problem with body electricals.
That is about the best I can do at this point. So let me know if any of these suggestions help.
Roland