Reply to "Coolant level sensor"

The sensors I've seen are reed switches, activated by a magnet. There will be a floating plastic part that raises & lowers with the coolant level, inside this floating part is a small magnet. The magnet will apply its attraction upon a reed switch and close or open the contacts. Those contacts are very fragile, not designed to handle much current, not even the current of a 12 volt lamp.

The picture below is that of a Ford reed switch, pulled from the bottom of a coolant tank. A plastic donut with an embedded magnet floated up and down around a stand pipe inside the coolant tank, the thin black stem of the switch inserted into the stand pipe.

In the second picture I've removed the thin black stem by force to reveal the tiny little reed switch indicated by the point of the pen, its encased in glass. This switch had gone bad & indicated low all the time (closed contacts).

cowboy from hell