ADDED VOLT METER BY USING IGNITION SW POSITION 2 AND GROUND.
Just noticed this^^.
'62 ignition switch cpould be different.
But in general I2 on the ignition switch is connected only with the key in Start.
Any voltage read at the I2 terminal with the engine running is voltage reduced by the current flowing through the ballast resistor.
Here's the back of a replacement switch for '67 as an example
View attachment 1716090296
Engine Running voltage should look something like this.
View attachment 1716090299
