alarm goes off by itself

2000 mustang gt, with viper 771........i am an installer and this is my car and i cant figure out why this is happening. at first the manager told me i should just catch the domelight for my door trigger. well after telling some else what happend he said to get the door trigger and diode isolate them.so i did. - door trigers so i put the cathode side of the diode facing the door triggers. i went to hook up factory disarm but the plug was empty where they said the wire would be. this is what i noticed.if i start my car, turn it off, then arm it my alarm goes off about 45 min later. when i turn it off and back on it doesnt go off by itself.  so switching to the door triggers didnt fix the problem. i have the shock sensor mounted on its side if that means anything. someone help please

The problem is that 45min after you shut down the engine the GEM shuts down thereby false triggering the alarm. What you need to do is isolate the door trigger from the GEM = put the diode inline between the door pin and the GEM and pick-up the trigger on the pin side. This way once the GEM shuts down it won't send the signal to the door trigger. Or another of doing this is by using a relay, because it will not trigger by the GEM shut-down. Read this write up:https://www.the12volt.com/installbay/forum_posts.asp?tid=74454&KW=ford+gem+shut+down

ok.....it looks like the wires change on the other side of the GEM.....i cant even find the door trigger.......im totatlly lost.........if i understand you right i nedd to, put the diode  somewhere in the kick panel before it goes into the GEM, then just leave the alarm input hooked up where it is........i cant find the wires anywhere else but where i alrady caught it.....

Is it hooked up to the trunk trigger. This will cause the same problem.

yes it is hooked to the trunk trigger........i disconnected it though to help eleminste possible causes.......and it still went off.......

Read the LED to see EXACTLY what is triggering it (refer to your table of zones)

Im pretty sure its door trigger too
https://64.85.6.129/extrainfo/diagrams/26500_MUSTANG_FORD%20DOOR%20PIN%20ISOLATION.pdf


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Do what captainzab shows in his link. The colors are as follows.

Door Trigger yel/black (L), gray/red (R)   -   20P plg, pin 13 & 5 at GEM
Trunk/Hatch Pin BROWN / white   -   12 pin plug, pin 3 at GEM

hi done lots of mustangs standard and auto this is the only way i got it to work perfectly take a relay pin 86 and 30 tie together and cut door trigger hook car side to these two then hook pin 87 to other side of door trigger and tie in alarm trigger here hook 85 to ground when doors are opened relay completes circuit when closed it breaks connection between alarm and door trigs gem not strong enough to trigger relay works perfect every time

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good luck
kirk

BulletTooth wrote:

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Do what captainzab shows in his link.

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I agree.

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Certified Security Specialist
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