Actually, the Flashing LED serves both functions in 83 and newer water
cooled Vanagons. It will flash if the engine temp gets too high and also
if the coolant level is low. There is a large third possibility though
and that is a wiring fault. I have seen a bad connection at the
instrument cluster cause this flashing as well as a sender wire that has
rubbed long enough for it's insulation to be gone. A momentary short to
ground starts the LED flashing and the ignition key must be reset for it
to stop (except on the early type of coolant level control unit). The
temp gauge needle moves very slowly by design so momentary shorts do not
have a noticeable effect on the temp gauge needle position but they
trigger the control unit to start flashing.

There were 2 types of coolant level control unit used and the exact
behavior of the LED depends on which type you have. The control unit
lives above the fuse panel but higher and to the left where it is very
hard to see unless you remove the small defroster vent on the top of the
dash to the left of the speedo. The control unit looks like a relay and
has a large #43 stamped on the top. The original part # starts with a
251 while the later one has a 191 part number.

Mark

Thomas Ryan wrote:
>
> Ron,
> ...........
>
> First of all the flashing red light on your temperature guage is not, repeat
> not an "overtemp warning light"! It is there to indicate a low level of
> coolant in the expansion tank. That's the tank inside the engine compartment
> and you can see the sensor wires leading to it. So if that expansion tank is
> empty, then that's why you're getting the light.
>ght me for more info. I've become a reluctant expert on this problem.
> ............
> Tom Ryan