I would wonder what you are testing for,operatoin or leakage,leakage is easy.mix a strong mix of dish soap & water together in a squirt type container ,squirt the fluid on the suspect area & watch for small bubbles.Testing the 12volt circut requiers removal of the valve.Apply 12 volts to the wires & simply blow through it.It doesn't matter which wire is which because the magnetic coil don't care about polarity.If you can blow through it with out 12 volts applied it's faulty& needs replacement.
The best way to test for a LP gas leak is to mix up some very soapy water and pour it over the suspected area. This also works to find a small air leak in a tire too. You will see the leak because there will be bubbles forming from the leaking area.
Set your multimeter on the 20 Volt DC scale.
Not a good choice but possible. This is a 120 volt AC controlled valve The version with 12-16 volt control would be a much more usable item
Never
12 volt
12 volt
No. You need 12 volt AC to run a 12 volt AC motor, not 12 volt DC.
12 Volt
Definately 12 volt.
12 volt test light
use two 12 volt batteries in series.
1971s had 12-volt systems.