help- blue field wire grounded?

That is LOW. "Here is why" low voltage to the ignition / regulator circuit causes OVER charging

In the girls we talk about on here, there is only ONE ignition switched power supply under the hood in "run" that is the (normally dark blue) "IGN1" wire coming out of the bulkhead connector

This feeds several things over the years depending on smog devices, etc, but generally, the ignition system, the VR "IGN" terminal, the alternator "light blue" field.

If that voltage is LOW this is ALSO the VR "voltage sense" and the VR tries to charge so that it rises to the setpoint, IE nominal 14V. So with the VR IGN terminal "happy" at 14V, the voltage drop backwards around to the harness to the battery results in HIGHER voltage to the battery.........by the amount of the measured drop.

Your 8V sounds like "it may change" that is, I bet if you start wiggling the bulkhead connector, the key, or the ignition switch connector, you will find that it goes higher/ lower

To put this another way, the normal way that I measure this drop is to probe the IGN feed as close to the VR as possible......and the blue field would do that, then put your other probe on battery PLUS. This is with the key in "run" and engine stopped. This gives you the amount of the drop directly. Again if you "wiggle test" you are likely to find out "just where" this might be