LC8i Tuning

[LoveMyCar25]

Please helps! So I'm running an LC8i(from previous install) to add a subwoofer only in my 2019 Camaro w/ Bose System. I have the front left and right high levels running into the main input to get the main output low level signal to my subwoofer Amp. When trying to tune my LC8i and the the right voltage, it will barely move and then it just goes sky high and back down. The maximized light is on almost immediately. I'm so confused. I can't really run the 40hz at -5db tone bc my Bose front speakers are still connected and I don't want to blow them turning up volume to 75%. Anyone have any ideas or do I have the LC8i wired wrong. Max voltage for LC8i is 8.5Vrms and my Amp goes from .01 -8.0 volts input sensitivity.