2006 trailblazer, adding sensors to alarm

First post, but have been reading and soaking up info for a while now. Hello, Im about to install an Autopage C3 RS1000 and INT-SL in my 2006 trailblazer and I have 2 questions. When installing extra sensors are you guys wiring the red to a constant 12V or are you tapping into a supplied 12V from the alarm? Like the shock sensor port? I am adding the 507 tilt and the 509 ultrasonic. And second question is, i've read somewhere, but cant remember where, that on my 06 model I have to hook up the 2nd accessory also for remote start. Is this correct? Thanks guys

I've never had much experience with multiple sensors. I think they can all take their 12 volts from the output of the alarm brain, but hopefully someone else here will know more. You will definitely want to power both accessories (the orange and the brown) on 2006+ Trailblazer. If you don't power up the brown, the car's engine will begin to crank the very instant the remote starter turns on, without the normal delay. This seems to work well enough at the time of installation, but then after time, the cars come back with various customer complaints. I never really could figure out what the real problem was, or understand just what the customer's issue was........but for sure, hooking up the second accessory wire made the car not come back anymore. You might find that some installers are not in agreement about whether GM vehicles need the brown accessory wire powered up.......but that discussion is only for the '05 and older models. 2006 definitely needs it for sure.

Thank you Chris, that explanation is exactly what I needed. OK im doing my install tomorrow, can anyone chime in on the extra sensor part? I really dont want them connected 24/7 to a constant 12V. But dont know if there is any harm done to the brain if i power 3 sensors off of the 12V supply to the shock sensor.

I was just thinking, I could connect the extra sensors to constant 12V. And instead of wiring the blacks to chassis ground, I would connect the sensor black to the alarms ground when armed?