My newest issue on my 86 GMC 6.2L is the low coolant light wont turn off. I have completed disconnected the wire from the sensor in the radiator and the light is still on. I do not have a low coolant problem, actually have a full radiator and a full overflow tank. Any suggestions as to how I can fix this. I am sure it is probably a wiring issue. Thanks for the help in advance.

I'm pretty sure the sensor needs to be plugged in for the light to go off.

Check all your connections. There may be a little air in your system. Tighten all the hose clamps.

If you have unplugged a sensor.

You have either 1 wire or 2 wires.

If it is 1 wire. Test it with the wire isolated, and the wire grounded.

If it is 2 wires, test it with the wires separated, and the wires connected together.

If it doesn't go off with messing with the sensor connection wires...
then your problem isn't the sensor.

Look for a broken wire, or a wire with the insulation rubbed off, or perhaps something in your dash.

The low coolant sensor in my Volvo truck was pretty simple.
2 wires descending into the expansion tank.
If water covers the ends of the wires, then a connection is made, and the low coolant light turns off.
If water does not cover the ends of the wires, then a connection is not made, and the low coolant light is on.

Oh, that brings up a point.
Does 100% ethylene glycol conduct electricity?
Obviously any ethylene glycol/water mix will conduct electricity, although I've heard that distilled water isn't very good at conducting.