temp hand problem??

[ccrain]

I have a 99 ford explorer with 5.0 v8. I have had the car 6 years. The temp gauge has never worked "right". It will only go up inbetween the C and start of the dome looking thing when fully warmed up. Here is a pic I found on internet, mine goes just a little farther when warmed up. Bad temp sending unit??. Also last summer the gauge would run up farther than usual and it made me curious. Well the service engine light come one and advanced auto said I had a overheating problem. So the gauge is not registering right, when it reads normal(like in other fords the hand works right), its running hot, when at normal operating temp it looks like the pic below. PS i fixed the overheating problem myself by flushing the system a few times. The coolent was VERY nasty, the heat works fine. Just would like to have it reading right,

 

[deweyville65]

Did you try grounding the sending unit wire going to the gauge? if the gauge reads HOT with the wire grounded, then the gauge is good, and there is most likely a problem with the sending unit.