is anyone familiar with monsoon sound systems?

[knuckleheaf27]

for starters this question doesnt pertain to GM trucks, i just dont want to join another forum for a vehicle i dont have..... anyway my sister has an 04 Pontiac GrandPrix GTP. I am trying to install an aftermarket head unit in it, it has XM, Onstar, and the monsoon system..... i instructed her to get the interface module for the door chimes and onstar and she has.... i wired everything up( head unit and interface)......ive installed allot of systems in many different vehicles but this one stumps me.... the head unit powers on and functions just fine and the door chimes and such work, but no sound comes from the speakers... almost like the factory monsoon amps are not turning on.... is there a remote turn on for the monsoon amps i need to tap into or what????? any help is greatly appreciated and thanks in advance....

 

[knuckleheaf27]

i figured it out...... while troubleshooting i jumped the remote turn on from the aftermarket HU to the power antenna wire on the wire harness and the monsoon amps tured on.... witch doesnt make much sense to me because the car has no power antenna. but at any rate the system works fine and sounds great.....