Infrared Sensor Interface Problems

[popnbrown]

I dont understand where the ground from to the digital io's come from.

I noticed that John C said that the two black wires in his picture go to the terminal block but don't we see that they are connected to the terminal block?

There is a pic in this post where it's all visible except the power distribution block.

The two white wires in the zip tie go to 12v from the battery. The two black wires in the zip tie go to ground on the terminal block.

http://www.chiefdelphi.com/forums/sh...12&postcount=4

So where does the ground to digital i/o come from?

I also don't understand why we need to use all four positive/ground pins? I got the board to power up using a 7.2V backup battery where the positive is connected to pin #1 and ground is connected to pin #3 and had it learn some buttons, so I don't see why it is necessary to use all four pins.

Thanks for the help ahead of time,
Sravan