O9 Head (on a APX7500 V/U) VIP Input Help. In CPS, R33.00, I have set the VIP INPUT functions as 1: Aux Siren Sw and 2: Horn Ring. Pinout of the VIP yellow plug on the back of the O9 head shows Pin 8 & 9 are the signal input pins. I have tried shorting the #2 GND pin to both 8 & 9 and get no...