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Deciphering factory alarm pinout

Printed From: the12volt.com
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=88665
Printed Date: May 10, 2025 at 10:29 AM


Topic: Deciphering factory alarm pinout

Posted By: Sad, little man
Subject: Deciphering factory alarm pinout
Date Posted: January 09, 2007 at 5:22 PM

I've decided I might as well wire up the power door locks in my car ('96 Mazda Miata.) The story is, it came with a factory dealer installed alarm, that got fried before I even bought the car, so I replaced it with a compustar, but only for security reasons, and I didn't bother with anything fancy like the door locks.

But, I've decided it might be nice to have keyless entry, and the acutators are already in the doors from the factory alarm, and I already have an alarm in place, so it shouldn't be hard. And to make it even easier I was hoping I could use some of the wires that hooked to the factory alarm like I did for a lot of the other features (the factory alarm and the compustar both completed grounds to operate the horn, parking lights, etc, so I just soldered them over to the new alarm.)

Below I have the pinout diagram of the factory alarm. I know for a fact the actuators are two wire reverse polarity, but I can't make any sense of these wires. I'm just looking for the two wires that go to the leads on both actuators. I haven't seen any relays under the dash, and the factory alarm was pretty big, so I'm thinking it had relays inside for the doors, and there should be two wires I can splice off into a new set of relays to hook to the new alarm.

posted_image

From what I've learned on another forum, connecting a ground to all four of the "common" and "N/C" wires does nothing, connecting positive to the "N/C" ones does nothing and positive to the commons causes a short. Dunno about the polarity wire. So anyone have any idea wht it means by common and N/C on a reverse polarity system?



Replies:

Posted By: captainzab
Date Posted: January 09, 2007 at 6:21 PM
its a relay circuit, most alarm has doorlock relay like that. on a relay, 87a is normally closed so it is connected to 30 which is common.
top left, read the basic about relays if you are still confused.

anyways, back to your diagram
Common is your output, so 13 is your unlock output and 15 is your lock output. 18 is your input. apply ground or 12v to this wire depending on the car's lock wire.

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Note: You Always Dont Get What You Pay For.




Posted By: Sad, little man
Date Posted: January 09, 2007 at 6:38 PM
Sorry, I don't really understand what you're saying. I've read all about how to hook up reverse polarity locks on this site, and it says nothing about any more than two wires coming from the alarm module. If I understand correctly, you're saying there are external relays somewhere, and grounding 13 or 15 should get the doors to lock and unlock, so I should just splice 13 and 15 over to my new alarm's lock and unlock negative outputs? Seemed like what I read elsewhere was grounding them does nothing. I'd look up a wiring diagram, but this system was dealer installed for ony one year, and there aren't really any wiring diagrams on it.

Edit: Ok, I think I got it actually, 13 and 15 should be the wires that go directly to the actuators, and those are the two I'll need for my own relay setup, correct?





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