Factory Alarm Disarm Wire Testing

ok, this may seem like a noob question but is there a better or standard way of testing for a factory disarm wire on all or each manufactor? the best way i know how kinda sucks because it involves doing the entire alarm or keyless and then lock/arm the vehicle and wait 20 to 30 minutes and attempt to unlock/disarm the vehicle. anyone got a better method i would love to hear it. as always  thanks in advance.

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"I cannot teach anybody anything, I can only make them think."
-Socrates-

Locate the wire you think is for factory disarm, and connect your circuit tester to it. (multimeter, test light, etcetera.)

Insert the key in the driver's door and turn it to the unlock position. The wire should test as a ground as you turn the key.

Still, you should at least first verify that the car even has a factory alarm at all, because they are often an optional feature.

--Open a window. Close trunk, hood, and doors. Lock doors with factory remote. Wait 30 seconds minimum. Reach inside the window, unlock the door with your hand (as if you were breaking into the car), open the door, and see if there's an alarm or not.

yea i know how to test for the wire but on some of the newer vehicles the disarm wire is located in the door itself. what i am wanting to know is there a way to know 100% or not whether a vehicle has this wire (since alot of the time they are optional) without having to test every wire or locking the vehicle and waiting to see if everything works right or not. years ago this really confused me when doing toyota camrys because they worked fine in the shop and during testing but shortly thereafter the customer would call back and say that the car would lock everytime but wouldn't always unlock when they returned to the vehicle. now at this point no horn is going off or anything like that but i then found that hooking up the factory disarm wire to the unlock (diode isolated) fixed every bit of this problem. well, now that DEI sheets just about always list a factory disarm wire for every vehicle i would like to know how to tell 100% right away if it has it or not. that may not be possible but any info on this wire would be great. thanks again.

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"I cannot teach anybody anything, I can only make them think."
-Socrates-

Sorry to get off topic, But...
Your story abuot the Toyota camry. You say that it locks but doesnt unlock. This has to do with the child safety.
https://www.the12volt.com/installbay/forum_posts.asp?tid=44622&KW=camry

It passively turns on after awhile. I did a camry recently and i ran into the problem about not unlocking and that post solved it.

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Note: You Always Dont Get What You Pay For.

but on the camrys i use the factory disarm wire and everything works fine not the child safety wire. do these wires test the same? i have put a bunch of keyless entry system in the camrys because we used to do all the local toyota dealerships keyless add ons and most of them have this feature but i figured it was because the passive alarm came standard on these vehicles.

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"I cannot teach anybody anything, I can only make them think."
-Socrates-