That is 12 volts from the chassis ground.Hey Dark,
When you say you have 12 Volts or 12 Bolts on the drivers side…..is that 12V to chassis ground?
On the other side. Is your measurement across the the rear backlight of from the terminal to chassis ground?
with the car off, what is the resistance across the backlight’s terminals with one terminal disconnected from the car?
BTW a small crack in the conductive trace can be very easy to miss.