convert ground when closed triggers

My 2012 Ford Fusion's trunk and hood triggers are ground when closed, but the Autopage RS730 alarm I installed accepts ground when open trigger input, so I used Bosch Style relays to convert them. Pin 85 and 86 to +12v and (-) factory trigger. Pin 30 to ground, and pin 87a to alarm trigger input. This works fine as long as the relays and battery are good. However, today when I was not home, the battery died and the alarm went off more than 10 times until the backup battery also died. I wonder if there is a better way to wire up this kind of triggers without wiring new switch pins. On the note my neighbor left on my door, besides complaining about what I mentioned above, he seems to be unhappy about the warn-away of the motion sensor. He parked his car next to mine. The warn-away of the motion sensor is supposed to be triggered when he gets on or off his car. If he is unhappy about the three chirps, I think I have to give up the function.

There's always this way :  https://www.the12volt.com/installbay/file.asp?ID=1121Soldering is fun!

kreg357 wrote: There's always this way :  https://www.the12volt.com/installbay/file.asp?ID=1121

Thanks. However, I think that is for (+) trigger input. Should I use relays to wire them to (-) trigger?

You would use the positive door trigger instead of the negative one. The link converts the rest at ground (normally closed) to a positive trigger one. The diodes provide isolation, resistors allow a positive signal when the door is opened. The circuit isn't intended to operate a relay.

kreg357 wrote: There's always this way :  https://www.the12volt.com/installbay/file.asp?ID=1121

Another question about the wiring scheme is whether the resistors can become very hot.

With the resistors being 10K ohms, no. 0.02 watts per resistor approximately.

Ween wrote: You would use the positive door trigger instead of the negative one. The link converts the rest at ground (normally closed) to a positive trigger one. The diodes provide isolation, resistors allow a positive signal when the door is opened. The circuit isn't intended to operate a relay.

Thanks, but this question is not about door trigger. For door trigger (+), I used dome light output from SJB. This question is about hood and trunk triggers, which are only available as (-) trigger input.

The same link would apply, add extra diode from your domelight. Doors, hood, and trunk would all report as positive door trigger.

Ween wrote: The same link would apply, add extra diode from your domelight. Doors, hood, and trunk would all report as positive door trigger.

You mean wire factory hood and trunk triggers to alarm's (+) door trigger input? The alarm has dedicated hood and trunk (-) trigger input wires. It's better that I can use them, so that I can know from the LCD remote. For hood trigger input, it also serve as safety shutdown mechanism.

Ok. There are relays available that trigger on much less current than the bosch type. You'd need to look for a 12 volt coil, spdt contacts, with a minimal coil current. Use one on the hood pin. I'd still wire the trunk with the diodes and resistor, converting it to positive. Unless of course you need to know specifically if the trunk is triggered. Maybe some members will chime in with other suggestions, other than the obvious addition of independent hood and trunk switches.