1997 Mercury Mystique Temperature gauge not registering

E-FIN

MEMBER
1997 MERCURY MYSTIQUE

Engine Cooling problem
1997 Mercury Mystique 4 cylinder Front Wheel Drive Automatic 128,000 miles.

My temperature gauge is not working. Initially the gauge did not work and the check engine light was on. I replaced the temperature sending unit at thermostat housing with a junkyard unit and the check engine light went off, but the gauge still not working. Radiator fans turn on and off and seem to work normally. Gauge moves ever so slightly when the key is turned on and off, but never reach near normal operating temperature. I live in a cold climate and I can tell you the heater works great so I am pretty sure the thermostat is opening properly and the engine is coming up to operating temperature. Can a sending unit operate the fans and not the gauge? Also I just replaced the water pump, timing belt, thermostat and coolant.

1 Reply

BEAGLE123

MEMBER
1 POST

I am having the exact same problem. I have changed my thermostat and temperature sensor. However, the temperature sensor is supposed to turn on the radiator fans, and feed the temperature gauge, but the fans never turn on. It seems like a warm engine temperature never registers. Also, if I disconnect the wires to the temp sensor while the engine is running, the fans turn on. I believe that means that the sensor is always registering "cold" so the gauge always registers is showing a cold engine, and the fans never turn on.

The strange thing is that when I disconnect the sensor, the fans recognize a "hot" engine (and turn on), but the temperature gauge on the dashboard still says cold (all the way to the left).

Any ideas?

Thanks,
Eric