Yes it is actually ground. The computer filters some of the electrical noise off and uses it as signal ground for the sensors. There should be less than 1 ohm between the black/white wire and battery ground.
took me a long time - the answer to my problem is this- the black TPS wire is internal ground - wire 46 at the EEC. wires 20/40/60 are actual grounds. If you didn't get a good ground on them, you can blow the internal ground.
If you have voltage on wire 46- ground the EEC test connector ground to a good frame ground and it will take care of the blown internal. FIX the grounds on 20/40/60.