siren diagnostics, 2002 camry, compustar pro

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Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=110146
Printed Date: July 18, 2025 at 6:16 AM

Topic: siren diagnostics, 2002 camry, compustar pro

Posted By: tedmond
Subject: siren diagnostics, 2002 camry, compustar pro
Date Posted: December 28, 2008 at 11:32 PM

hey all, well i thought i should share my weekend of testing a ** siren.

long story short. 2002 camry lev6 with compustar pro P2W900FM-AS.

siren stopped working for a few days so i thought okay i can wait until the weekend to fix it. If its very quiet, you can hear a slight chirp. first thing i did was pull out a DMM and tested the 12volt line and the dmm gave me a solid 12 reading. so, i thought maybe a fault ground...(bad groudns can give cause many problems) ground tested fine as well. took the siren out, connected it my booster box. The siren works loud and clear. I then wire in a relay for the siren and get a direct high current source from the battery. i know its not needed but i wanted to know why. It still didnt work. This is when i got frustraded. tested the 12v siren line again and its a solid 12v. so now im thinking to myselfl its not the unit, nor is it the siren. what can it be? i even connected the 12v trigger from the relay to a direct 12v source. the relay clicked and nothing. so i gave up. connected everything back the way it was. clicked lock; no chirp. clicked unlock; no chirp. I was now ready to just scrap the unit and get a new compustar unit. so i started playing with the 1way remote. i pressed unlock 3times in a row and i get an unlock cchirp.

wth right? as of now the siren works with lock, unlock and remote start. but when i hit the car, the warning is not loud at all. So i found an old siren lying around. wired that bad boy in and still same thing. prewarning is some chirp that isnt even noticable. at times it will chirp really loud...

so Howie, KTM, I am an idiiton, Chris, twelvolts, ckeller and many other memebrs, what do you have to say about this siren? as of today its been constantly loud even with warnings. (original compustar siren)

sorry for such the long read, and dont kill me chris for my puctuation lol. just trying to get it out there that this is the worst diagnostics i have ever done....

Replies:

Posted By: KarTuneMan
Date Posted: December 29, 2008 at 7:50 AM

It would be MY suggestion..... replace the siren. Why, you ask.... just because!

12v, and grond is there! pretty technical answer huh? posted_image

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Posted By: 91stt
Date Posted: December 29, 2008 at 10:26 AM

If you have a spare siren than swapping it out to test is the easiest way to confirm.
If you want to check the condition of the siren output under load you can substitute a known resistance value in place of the siren. I would suggest a resistor between 10 ohms and 30 ohms. Measure the current going through the resistor and use ohm law, I = E/R, to confirm if the output is acceptable. If it is than the siren is definitely bad. If the current is nowhere near the calculated value, the transistor is probably bad in the brain. Hope this helps. posted_image

Posted By: tedmond
Date Posted: December 29, 2008 at 1:55 PM

thing is, i mentioned i alaready swapped the siren out with another siren and same issue. however, the unit does send out a stong 12v source. its not the unit for sure, i used a relay for the siren as well. this is some weird issue. but anyways the siren works for now and its okay with me. who steals camrys anyways? so it dont matter.