"Coolant Sensor Bad"

Hi All,

I have a 1997 Jeep Grand Cherokee Laredo 4x4. For the last year or so,
every so often (a few times a week), I get the message "Coolant Sensor
Bad" in the center console (the area that shows "miles to service" and
when doors are open and such). According to various sources, the
coolant sensor in question is the coolant level sensor in the overflow
tank. The other coolant sensor that is in the engine block throws a
"check engine light" error code if it's having problems (I've verified
that by unplugging it), so I'm reasonably certain that that's not the
one causing the problem.

Now, I'm sure most of you are thinking, "why don't you just replace the
coolant level sensor?" I did that right away last year when it first
started happening. It didn't have any affect on the problem whatsoever.
I've also brought the car to the Jeep dealer, and surprise, surprise,
it didn't happen while the car was there, so I got to pay the
diagnostic fee and go home.

One interesting thing is that the "coolant sensor bad" message didn't
occur all winter, so it does appear to be affected--at least to some
degree--by temperature.

Anybody have any ideas on how either to fix the problem with the
coolant sensor, or to at least get it to stop telling me about it? I
don't particularly care if there's a problem with the coolant level
sensor...I'm perfectly capable of lifting the hood to look at the
overflow tank, but the beeping from the console is kind of annoying.

Thanks,
Tom