With the vehicle prepped and ready to be tested, hook the negative lead
of the test light to a good ground and proceed with testing.
The bulb DOES NOT light The voltage is 0 - 1 volt
The bulb MIGHT be glowing The voltage is 1 - 3 volts
The bulb BARELY GLOWS (or there The voltage is 3 - 5 volts
is a reflection from the overhead
The bulb GLOWS MUCH BRIGHTER