Hello, all. I recently purchased and installed a supposed "never installed" Intelliguard 750 security system. Only after purchasing it and going through the contents did I find the valet switch missing, but the siren was the 514c universal instead of the 518c. When I installed it, the instructions say to connect the brown wires from harness 1 to the brown wires of the siren. Problem is, the universal siren has a black and a red wire! Connecting them does no good - no sound. Then I grounded the black siren wire and connected 1 brown wire - no sound. I then connected the other brown wire and got some sound, though not very loud. I tested the siren with a full 12V using a Power Probe 2 and the siren wails loud and clear on 12 volts. Is the universal siren just not compatible with the two brown wire system of the 750? Also, the Horn Honk function does not work. I have it connected to the right ground wire (applying direct ground to the wire with the Power Probe sounds the horn). But when I connect the signal wire, there is no sound when I trigger the alarm. I checked to see if the brain was pulsing ground and there appears to be no ground signal. I even attempted wiring in a relay in case the signal was too weak to trigger the horn - still no sound. My lights flash and my starter/ignition interrupt works great but my security system has no audible warning devices. Was I hosed and the brain is fried or am I missing something?