Thermostat or Temp Gauge

Now that weather is cooler, nights 30 - 40 degrees, After the truck is cranked when cold, the temp gauge goes to the full hot position and stays there for 5 to 6 miles then quickly goes back to average temperature reading. What do you think is happening here ?

 

sounds electrical in nature
I'd start with checking the temp probe wire for damage
then find the test procedure for the probe

and welcome

 

Craig, Thanks for your response. Where would I find the temp probe wire?

 

You could also get a scan gauge or ultra gauge so you can see what actual running temperature is.

 

IDK the placement, you will need to look that up in a service manual from someplace.

given that resistance rises with temperature I'd speculate that the prob is failing. it has an open connection when cold that closes when warm and giving a normalish reading
but rodent damage to the wire is also a possibility

 

I'm betting it's the sender.

Your gauge is a dummy gauge in that, it's "kind of" accurate based on a single wire probe or resistor that it works off of.

These trucks have a sensor, and a sender.

The sensor communicates with your computer to tell it how it's running, and this information is available via your OBDII port.

The sender is located separate from that of the sensor, and its sole purpose is to move the needle on your temp gauge.

You can have a bad sender telling you you're overheating, whereas your vehicle could be in perfect health.

The opposite can happen where your truck is overheating, but the gauge could be faulty and not warning you.

 

https://www.youtube.com/watch?v=wewinn6Gf-w

 

I have replaced both the sender and sensor and the problem has not changed. I do not have access to a vehicle computer device.