Hello! I recently purchased my first Ford (and a truck at that!). It is a '91 F150. The temperature guage reads below 'C' at all times. The air temperature is consistent with the engines operation (EG: cold in the mornings, warms up after ~10 minutes run time). I have checked the wiring coming from (what I believe to be) the sensor and all looks well. If someone could give me some advice as to what some readings should be (I do not know if this is a voltage or current circuit) as well as confirming the sensors location I would greatly appreciate the help. Seeing as how the Mrs. let me get the truck it makes it that much harder to justify buying parts! Thanks for any input you may have.

- Tim

 

Tim ,
What engine does your truck have ? Manual or automatic ? If the truck runs fine no need to worry about where the temp gauge reads ...Ive seen some stay where yours is , some a litte higher . The temp gauge sensor is in different locations depending on the engine .
Paul

 

Tim ,
Sorry , After I posted I saw you have a 302 ...Didnt notice it until I posted the previous .I beleive on your engine the little temp gauge sensor is screwed in the block on the right hand side , just a single wire connector .
Paul

 

Tim, It is very easy to find out if your sensor,
(sending unit) is bad or good. Disconnect the single wire (green) going to your sending unit
and ground it to chassis ground. Turn your key to
the on position without turning on the motor, the
temp gauge should now go all the way to the right,
if it does then your gauge is okay, if it dosen't
then it is bad. If the gauge goes all the way to
the right then your sending unit is mostly likely
at fault. You should probably run a continuity
check before replacing any parts, it could be a
poor connection.
good luck.
EBTE tech

 

EBTE tech,
Thanks for the advice. Assuming I do not get frozen too much in MI this weekend I will try your suggestions. From what you posted I assume that the temperature sending unit is more of a thermistor than a sensor. Is this correct? Let me know if you get a chance (more out of curiousity than troubleshooting). Also, I found another posting that refers to the sending unit going bad will cause the engine to idle faster. This also makes sense as the computer would try to richen things up / speed up to get the blood warm. I am having this problem on my truck as well. More of an annoyance (and lower mileage) than anything.

Thanks again -- have a great weekend!
- Tim

 

Most temp sensors are a type of thermistor, can't think of any off-hand that aren't !