here's the scoop, I'm driving home and the engine light comes on. Then I notice the temp gauge is maxxed out as well. I stopped and check under the hood and all seemed normal, So I drove on home, I checked the radiator and let it cool down but no change, the temp gauge doesnt move at all and engine light is still on, thermostat maybe, a sensor of some type ????

 

I don't know about other years, but from what I understand about my 86, the engine temp light and the gauge are different sender units (gauge is one wire, warning light is two wires). Given that, I suspect you might have an issue beyond a bad sensor.

 

would nt they both connect via themostat???

 

That's exactly correct, but what the OP didn't tell us is what year is truck is and if it's the engine temp light that is on or just the 'check engine' light which I understand is on the later models to tell you to check your gauges. He may just have a bad gauge sender.

How would that work?

 

Unlike modern vehicles with computers in between the sensors and the gauge, our trucks can pretty much only have one gauge per sender (you make things too complex and variant when you introduce more gauges). This does have an advantage in that if they both read "too hot" then you very likely have an issue (it is quite unlikely that both would fail high at the same time unless you had a pretty extreme short going on).

The location of the individual senders are showing in this thread: https://www.ford-trucks.com/forums/9...mp-sensor.html
There is also a sensor hooked up to the injector pump for the cold idle.

 

And doing some googling and reading, it looks like the overtemp sensor might be setup to peg the temp gauge. No idea if this is accurate or not though (or what years it might apply to).

 

yea I read that one too, the temp gauge is even pegged when the truck's off
its the engine light, not engine temp light
sorry man its an 87 f-250 6.9

 

driver side head temp sensor. unplug it and see if the light and gauge go out.
the sensors and connectors are not the best for sealing, and if you hit a puddle just rite water will short out the connector/sensor turning the light on and pegging the gauge.
i found this out after washing the engine on my 88. it would do it on all 6 of my trucks.

the only thing that will turn your check engine light on are high engine temp sensor or low oil pressure sensor.

and once the light would come on, it would take 2-3 days for it to dry out and go off.

 

or snow melting into engine compartment maybe
will it kill me to drive it short distances for a couple of days, its gonna be 0 and below for a couple of days and I dont have a garage

 

thanx tjc unplug sensor and shazam, I discover a valve cover leak on the same side so it may have been oil that did it

 

good deal. i really don't think unplugging it will hurt, or you can try cleaning it with carb cleaner or some type of degreaser spray and compressed air and plugging it back in, or leave it connected and ignore it.

 

I had the same thing happen. Was offroading without the fan installed one winter and the light went on. If I unplugged the overtemp sensor, everything worked fine and the temp sensor gauge worked like normal.
I ended up swapping the overtemp sensor with one from a spare engine, so not sure if it got splashed or what not, but didn't really care at that point.