Chevrolet Repair: 94 Chevy Custom Van, chevy custom, custom chevy

Question
Robert,

We've got 94 Custom Chevy Van with a 350 engine and over 316K miles.  The Van still runs great on the original engine and only two trans...which is good.  We've had leaking coolant problems for about a year with replacement of the "plastic" radiator.  About a month ago the heating and coolant gauge start acting up in that it will only read about 1/8 or 1/4 at all times.  Normally it's dead center.  I started thinking that the thermastat was sticking "open" but that didn't make any sense.  Then I thought about a bad gauge (could still be) but I know there should be some sensor that the gauge reads from..that my question.  Is there a sensor that maybe be bad.  Have you seen this problem before?

Answer
The only way to test the gauge properly is with a gauge tester that you can dial in the proper resistance signal to the gauge and watch what it does.

You can try disconnecting the connector on the sensor, with the ignition in the run position watch what the temp gauge does...it should swing all the way to one side or the other. Now ground the terminal in the connector and the gauge should move to the other side.
If this does happen, most likely the gauge is ok and the sensor may be defective.

Hope this helps