I just got a 2005 edge with 3.0 auto 4.10s 2x4. last week. I noticed today that the coolant temp gauge is noy working...
Could it be the sending unit or something else? All help appreciated.
MAXB

 

is it not coming up at all?

it might be the sending unit that is on the intake manafold.....should be a $10+/- part at an auto parts store...

 

does the needle move at all? how is your heat?

there's a coolant temprature sensor on the block that sends the signal to the cluster. it could be screwed, or the wiring might be disconnected/bad.

otherwise, the thermostat might be sticking open. with the big ol' fan on the front of the rangers and some cold weather your tuck might not be heating up at all. (it sounds weird, but i had a 92 chevy 1500 in the shop the other day with this exact problem)