1993 Toyota Camry alarm(?) troubles

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Now I know, very stylish; An old Toyota! However, I intend to run this thing into the ground and have been taking the proper maintenance steps to do so for the most part. One thing that I've found very troubling recently though is the after market alarm system that has been installed in the thing since before I owned it. I do not have a clicker for the alarm system, and I'm not completely sure about the functionality of it. Please keep in mind that I have very minimal experience with the technical aspects/wiring of vehicles, but this is what's been happening:

I've had a time or two when I hop into the vehicle (very hot inside as I live in Texas) while the engine was cold and have the alarm go off on me when I open the door. This, in and of itself, isn't what I'm worried about as it's only happened two or three times and very infrequently. I can always turn this off by flipping the kill switch and turning the key to the on position.

What has been troubling me is the fact that after the engine warms up (this ONLY occurs when the headlights are on) and I've been driving for a while - maybe after 5 miles - with the headlights on, the horn will just start blaring. This stops though the second I turn the headlights off again which leads me to believe it's an electrical problem. *possibly unrelated* Some goofy stuff with the electrical system like the car doors unlocking has been happening every so often, but only while the engine is running.

The battery is a bit old and has accumulated some corrosion, but seems to be functioning just fine for now. I suppose that I'm taking a shot in the dark saying it may be connected to the alarm system, but between previous alarm system issues + the horn I figure it may be related.

This problem with the horn blaring does provide somewhat of an issue for my drive home from work (currently 4pm-1am, so I'll need the headlights on!) and I'd rather not be pulled over for blaring my horn down the highway at 1:30 in the morning.

How might I go about detecting what the problem actually stems from? Has anyone had this particular issue before? If it is the alarm system, would that be easily disconnected (as I assume it's connected to the engine as it kills it if the alarm is set off)?

If anyone could provide a bit of insight on this for me, I'd really appreciate it! =)

-Dan

PS. If you need any clarification on any of the above information, or if I'm leaving out anything important, you'll not hurt my feelings by treating me like the newbie I am to cars. The only recent maintenance I've had done on the vehicle was a repaired leak in the muffler system to keep it running clean.

Edit: A few additional details about the make/model:
1993 Toyota Camry LE
4 door sedan
4 cylinder engine
Automatic transmission

posted by  Danboy

For starters, can you find the alarm control unit?

posted by  windsonian

Unfortunately not as of yet. Although the thing has been acting up so I'll likely just have it removed at the first chance I get. I've gone ahead and picked up a Haynes manual for the 92-96 Camrys and first thing tomorrow (time off work! :clap: ) I'm going to be running some testing on the relay circuits to see if there's a short somewhere along the lines.

I've been informed that a big issue with Toyota cars is that there are usually multiple relays in a single component circuit with only one that controls it. It could be that the horn switch in the steering is shorting out. That seems to be the one that completes the horn circuit by grounding it. First things first I'm going to check all the fuses now that I've got a diagram. =)

I suppose this is speculation, but I'll go ahead and check back once I've found out a bit more in case anyone else may have questions about this as well.

posted by  Danboy

at least it sounds like you have some idea about ELV circuits, so you've got a headstart on most of the people on hear asking for help.

Good luck, and get back to us if you hit a wall.

posted by  windsonian

Well, I've taken the vehicle into a Toyota dealership and the eletrical system itself seems to be in perfect working condition. However, it does seem that the problem stemmed from the alarm system. It was acting up a bit, and there must have been a short somewhere in the lines as the alarm light would flash every time the horn was activated.

For now, the alarm system circuit which controls the horn functions for security has been disconnected. Once there's a bit more money in the bank I'll have it removed altogether as I don't have any kind of diagram or marking on the actual alarm box to give a hint as to what make/model system was installed.

If it persists, I suppose the easiest thing to do for now would be to remove the horn fuse in the fuse box under the hood to cut power altogether. There was some initial concern over the... well, forgot the name of the part but it was a spring mechanism built into the steering column just behind the steering wheel. With the alarm system acting up though the mechanic went ahead and looked into that as it much a much less expensive alternative and the likely cause.

If there's anything else that I come across I'll be sure to bring it up! In the meantime, I hope this helps in the off chance anybody else runs into something similar.

posted by  Danboy

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