So I installed a sony XAV-63 touchscreen unit in my '07 H3 but I am having a problem. For starters there is no switched 12+ at the stock radio because of the Onstar, chimes and some other bs. I wired the new unit with with a "brain box" designed to get around GM's trickery. Basically this creates a switched 12+ from the constant 12+ via a relay and a signal from the chassis computer. I wouldn't have bothered installing all this and just found another switched 12+ source but then I would lose the retained accesory power (so the radio still plays after you shut the vehicle off until you open a door).
This all works well.......sometimes. The problem is sometimes when you start the vehicle the unit boots up but is OFF. Other times its comes on and continues to play right where it was when the vehicle was shut off. This had me puzzled for a while but then I caught on to something. Everything works perfectly if you just go to the accesory position with the vehicle, everytime. Acc, off, acc, off, acc, off, works just like its supposed to. Then, while its playing with the ignition on accesory, if you start the vehicle it goes black, boots back up, but is off...
I believe this to be the voltage drop while cranking messing with the computer in the unit. This would be the only thing I can figure would cause the intermittent problem. Thinking that if the voltage drops to right on the boarder line voltage the unit can operate on it wouldn't take much one way or another for it to work or not. For example starting cold vs. hot would drop more or less current. However, just by fisheyeing a test light the constant 12+ I'm feeding the set-up drops as much as every other 12v I can probe exept the switched 12v it "creates" seems to dim a little more for some reason. So the question is can I just wire a capacitor at the radio to help this? If so, what size do I need? Any other ideas?
