I recently wrote about wires and I stated that sound is carried on the outside if the wire. I have received several Emails “telling me I am nuts among other things”. In truth no one knows where it is carried to an absolute certainty. Many fields of thought subscribe to the theory that the power is pushed through the wire and returned by the ground. My problem with this is that no ground should be required if all of the amps are used by resistance in other words if a lamp uses all the available, amps, by resistance, ohms, then the lamp should light with no ground necessary. The holes theory, which makes more sense to me, has a feeder from the ground that draws the power from the source and the power follows that to a ground. Or to put it bluntly the ground sucks. This is seen as nature as a lighting strike. A feeder comes from the ground and the bolt follows that to ground. A car system works the same a feeder on the inside of the wire is a path from the ground that the power follows to ground. This is why a ground is needed to light the lamp. This is simplified and to the extent I understand the holes theory. Electricians will talk about delta among other theories mostly as it pertains to 240 and higher voltage but they all still need a ground. I understand battery, DC voltage, as in cars more than I do house power, AC voltage. To further add validity to my theory this is why ground controlled systems perform better then controlling the power. IE fuel injectors I don’t think we could turn the power on and off as rapidly as necessary using a power controlled circuit. Also when using lower voltages the ground controlled systems seem to work better. I don’t know how a return reading from an O2 sensor or a TPS would work. You would have to measure the resistance and this would not be adequate as to the required accuracy.