my temp gauge in the cluster is not working 91 f250 7.3 non turbo where should i start looking.

 

Try cleaning the sending unit terminal and wire connector, also check for blown fuses.

 

If you pull the wire off the sending unit, and ground it with the ignition on, it should peg the temp needle. Remove the ground and it should peg the other way. If this occures, the gauge, wiring and connections are all good. The problem is at the sensor. If the needle doesn't move as described, the problem is either the wiring or the gauge.
It might help to chant I hope the sensor is bad, over and over, while doing the test.
Hope this helps.
Good Luck Frank

 

if the temp switch ends up being bad... you really need to have the new one ready to put in the instant you get the old one out. coolant flows out pretty quick when you take it out but its a pretty easy swap other than that

 

BTW... I don't know where the dash gauge sensor would be on the 7.3, but it's seperate from the engine coolant sensor, on the small V8's the dash sensor is on the drivers side front water passage in the lower intake.

 

Hello, I am new here. I have a similar problem on a 97 4.6 F150. I have replaced the old temp sensor. It was shorted at ambient temperature 200 ohms. The connector to the sensor was open, the wires were broken inside the connector. After replacing both the sensor and the connector the coolant gauge stays pegged to the cold side. I verified that the gauge is functioning correctly by using a jumper. It functions properly. I was reading in the Haynes manual that the reference voltage should be at or around 5 volts, my actual voltage reading cold is 11.3 volts at 19k ohms on the sensor. At operating temperature the voltage drops to 8.1 at around 3k ohms on the sensor. I am curious if the Haynes manual is correct about the voltage. Obviously it would make sense that the needle would be pegged to the cold side with the voltage at over the standard level.

Question 1: What is the correct range of impedance (ohms) for the sensor on this truck?
Question 2: Is 5 volts the correct range?
Question 3: Is this a 0-5v or 4-20ma input from the sensor to the gauge?
Question 4: If the voltage is incorrect is the ECM bad?
Question 5: I have as of yet been unable to find any bad fuses, is there a fuse or are there fuses in this circuit outside of the ECM.

Any replies would be greatly appreciated, this is my primary vehicle and I need it to get back and forth to work.