So I'm guessing sensors, relays and electrical are not vw strong point.

The coolant temp/level LED is flashing non-stop. Coolant level OK and
temperature OK. New temps sensor recently and opening or closing the coolant
level circuit (bad sender?) has no effect on the LED.

What are the other failure trends of this circuit?
Does the voltage issue failure trend have an effect on this LED or that just
related to the temp and fuel gauge?

I've traced the circuit from the sender to the black box on the left
firewall and all is good. What else?

Shawn