HI were the heck could I find the engine coolant temp senser on my 2004 F150

 

You don't have one. The coolant temperature is "inferred" by the PCM from the Cylinder Head Temperature (CHT) sensor values.

- Jack

 

So if I have a bad reading on engine coolant temp it is really the CHT

 

Yep.
I was surprised when I datalogged ECT and CHT ( older truck ) how close the two temps were. CHT is slightly higher because of heat soak, but still very close.

 

Hey today my overdrive light started flashing off and on. Took it to autozone and hook up the scanner. And got code PO117. ECT (engine coolant Temp) circuit. Now where is the this sensor? And why did my overdrive light come on and not my check engine light?

 

did autozone go into the transmission codes or just engine? does your cel come on when you first turn the key on without starting the truck?

 

Autozone said that the scanner did transmission codes as well as engine codes. Its not a cel. Its the overdrive light on my gear shifter that flashes. It does not start flashing right off. I can drive for a couple minutes and then it comes on. Dont no for sure if its speed or time truck on that makes it come on. what do ya think?

 

the 98 still had a ect. it was the last year before they started using cht's on the 5.4. the 4.6 started using cht's later on. i just wanted to see if your cel worked or not. if there wasnt any codes for the transmission i'd say you may have turned overdrive off maybe. i dont know how the system works on that year. i dont know what kind of scanner autozone uses but it should give tranny codes with the engine codes if there are any at all. is it shifting weird? or is anything different about the tranny that you can feel? delaying shifts, slipping, any delay in gear engagement, etc.?

 

There is no difference in the transmission that I can tell. Everything seems to be normal. Shifts great both up and down. When the overdrive light starts flashing I can still push the button to turn overdrive off and it does. Then I can turn overdrive back on. I have looked and found the ect sensor on my truck and found that autozone (which is right down the street) has one for $20. So i think I will start with that and then hope that is what it is. What do you think?

 

going by the code it sounds like the sensor. hopefully thats all it is.

 

I hope so too! It is just funny that it was my overdrive light flashing and not my check engine light coming on. Well I'll see if thats it! Thanks for your help!