my o6 dakota's temp light is coming on and off. my son replaced the tstat and no help. apparently the temp gauge is rising to midway on the gauge and the light is coming on within 45 seconds of starting the truck. the light will go back off but the gauge stays the same no matter what. no codes are being set. it sounds like a sensor to me but i thought it would set a code. any help is appreciated. 06 dakota 4X4 4.7 v8

well i guess i got egg on my face. after gettin home and checking the vehicle out it turns out it is the trans temp light is coming on and not the engine temp. i have taken a few raod trips with no problem. even climbed the mountains up to Ashvelle nc dwith no issue. the only time it comes on is in town. strange thing is it will come on befor the truck is even close ot being warmed up, some times with in a half a mile. it will also come on after reaching operating temp. if i shut the engine off while it is lit and turn it right back on the light is off and does not come back on. it might or might not come back on. it is ver intermittant. every thing operates like normal. the radiator is clean, i need to check the fan but it seems to be operating properly. any suggestions would be appreciated.

Shorting temp lead to ground tripping the light? Bad trans temp sensor?