My gauge temperature sender went bad (open circuited), and temperature
always read cold. Replaced the sender. Now at normal idle, the gauge reads
past the LED and almost up to the "hot" tick mark on the gauge. I don't
believe that the coolant is hot for the following reasons:

1. The radiator fan doesn't turn on when the needle is reading very high,
yet turns on when I'm idling in hot weather (as I would expect).

2. The voltage at the ECU from the ECU temperature sender looks normal. (I
have wired a breakout box to the ECU like a Digitool.)

3. I inserted a thermocouple (temperature sensor) into the reservoir tank
(not the overflow tank of course) and it reads 210 deg F. Now, this
temperature may be a little high, but not high enough to read as high as it
does on the gauge.

I've replaced the sender 3 times, once from a different manufacture. They
all behave the same. I checked out a different gauge, and it behaved the
same as the one I have.

I've searched the archives many times. I only found 2 references to the
"normal" operating temperatures for the coolant; they suggested a range from
200-210 deg F.  Can anyone else confirm this?

I see from the Bentley wiring diagram that the low level coolant electronics
are connected to the gauge temperature sender. Could a faulty low-level
coolant circuit cause my problems?

I've been working on this for some time, and it's got me stumped. Any
suggestions?

Thank you very much.  Have enjoyed the list very much.