false door trigger alarm f150/554t

I just installed a 554t on a 2003 F150 supercrew. Everything is operational, but after it is armed for a while the alarm triggers. My remote shows an open door, but the door is closed and dome light is off. I used the BLACK / YELLOW wire for the driver door and BLACK/ lt blue wire for rear doors and diode isolated them. Any ideas?

I would have to say that you are having problems with the GEM module. on some ford they have a mudule that sends pulses on the door trigger after a certain amount of time. this is what is setting of the alarm.

The BLACK/ blue wire should be the positive trigger going to the dome light. The yellow/black should be the wire for the driver's door switch(this is also the wire that the gem module pulses). The BLACK/ blue should be the only one you need. Try disconnecting the yellow/black and see if it still does it.Certified Security Specialist

Always check info with a digital multimeter.

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Thanks for all of the input. I was using the negative door trigger for both, which apparently was coming from the gem module. I switched to the positive trigger wire and have not had a problem yet. Thanks again.

Most Fords and other's as well have a "Battery Saver" relay. This powers down many devices like interior lights after about 45 minutes, or so. The GEM (Generic Electronic Module) Powers down, as well. When this happens, the 12 volt potential at the door ajar switch goes away, and the Alarm "sees" this as an intrusion, because the "state" of the trigger wire has changed. I have seen this rectified by isolating the actual circuit with a relay, or even a resistor.