Gas, oil, chg and oil pressure gauges aren’t working. New harness and new instrument regulator. Chassis Ground is made. Am I missing something? How can I test the ground?
You could have a broken wire (or bad connection) somewhere for the input side of the CVR. Check for 12V with key in ACC. If you do, check for voltage at the black/green wires going to each gauge: you should have a flickering voltage that averages about 5V. That post for the black/green wire may be shorted to the case, which can cause all of the oil, water, and fuel gauges to not register, so measure resistance between that post and chassis ground with the connector off that post.
The charge gauge is not part of this circuitry, and barely registers in the best case. To test, key off, headlights on, doors open, brake pressed, cigarette lighter depressed and you might see the needle move about half a needle's width.