Overcooling or broken temp gauge? 99 sport
 

Recently my temp gauge on the cluster has been acting up: it would run normal temp at idle then as soon as I'm at cruising speed it will drop to 1 to 2 notches above 100 degrees. Sometimes it never reaches operating temp, according to the gauge. I'm thinking the sensor is broken or the thermostat is getting stuck open. Before I tear it down, I am kindly requesting some wisdom from the forum. What do you guys think it could be?

Make sure the connector to the sending unit is securely attached to the sending unit. Take it off and spray contact cleaner in it. Or at least push and pull on it to make sure its seated all the way. If its not seated right it can read low and move around.

If that doesn't fix it, its probably a thermostat that's hanging open. Do not use failsafe thermostats if you replace. Many people report good results with a Stant Superstat 195F. I use the dealer thermostats.

Does it fluctuate when it drops down that low? I would suggest looking at the sending unit also. Corroded contacts could be causing the issue as well as it not being seated all the way.

Just replaced the temp sensor. All is well for now. Hopefully.Thanks!