I have same questions about Fusion brain.
I want to control my oem radio with carpc.(ON,OFF,CD,......)
This is oem radio plate.
I want to control this push buttons with fusion brain.
I m solder wire for each button.
For do that if i must buy fusion brain and relay for each button?
Sorry for my english.
May not need relays - they're probably all 12V low current. Hard to determine that for sure though.
I'm using optoisolators for controlling the push buttons for my HVAC unit. This is essentially the same problem as you're having. I just hooked up a 1kOhm resistor to pin 1 of my optoisolator (LAA110 - http://www.clare.com/home/pdfs.nsf/www/LAA110_R09.pdf/$file/LAA110_R09.pdf). It seems to work really well, when the digital output on the fusion brain goes high, the optoisolator (or a solid state relay) connects the terminals, emulating a push button