I'm at work now so I don't have time to look into your system, but I did a quick google search on your alarm and seeing the style that it is, I am pretty sure that it has the features to do this. Just look in your owners manual and see if it has instructions for aux output. If you have the install manual that would be better because that would tell you about the pulse/latch/etc. but if you had it installed somewhere else they often don't give you the install manual so you have to come back to them for any programming changes.
Originally Posted by funkyphil
Yes you still need yo use a relay. There are 2 reasons. First reason is that the aux output on the alarm is a ground circuit not a power (or positive) circuit - all they do is open the aux wire to ground. So you need to hook a constant positive wire to the + end of the coil on the relay and then the relay is triggered by the alarm grounding the - side of the coil. The other reason you need a relay is that the aux lines on the alarm are only rated for 200mA. They can't handle the load of much especially a CarPC and are only designed to trigger relays or very low powered features.
Also I feel that I must mention one precaution... If you are also using the ignition switch (r accessory position) in your car to trigger you PC, with this mod you will need a second relay or diode to prevent power from flowing from you remote turn-on back into the ignition system of the car, thus turning the power on to the whole car. If you are using a separate manual switch to turn you PC on/off then you can disregard this.