minimum voltage to trigger a 12 volt 30/40a relay

Hello,

Customer asked if the viper 550esp's remote start can be shutdown when the alarm is triggered.  I've explained that the remote start sequence will shutdown when the hood is open, brake is pressed, rpm is too high...

I was wondering if I could use the Siren's positive wire to Pin 86, Blue status to Pin 85, Pin 87 12 volt fused, Pin 30 to the Brake Light input and diode isolate it from the Brake switch wire.

If the alarm is triggered while remote start is running, it will send 12 volts to the Brake Light input wire to shutdown the remote start.  I realize the siren chirps etc, but I don't think it shows at least 12 volts when the siren chirps but when the alarm is triggered I get at least 12 volts.

would this work?

netZ