Hi Martin,

>>> could you explain how a ground can be "pulled up"
as surly a ground is a ground and should be less then .2v <<<

Some earths are "pulled up" from true earth via resistors inside the ECU called pull up resistors. (Think of it as part of a voltage dividing circuit)

One of there common jobs is to provide a "Floating" earth to help the ECU with its EOBD monitoring role.

Regards Mark

PS. if you search "Floating earth" on this site you should find some good explanations.