just today after I hooked my computer up to my pcm and used tunercat my temp gauge no longer reads anything. This to me is very strange as I'm pretty sure the sensor goes directly to the gauge and there is a separate sensor for the PCM. The only thing I changed with tunercat was my spedo calibration and changed the trans type to manual as it was before Auto. Any ideas??

 

No possible connection between the two. The sensor in the head only connects to the gauge, as you already mentioned. Did you check the wire to the sensor? Did you check the sensor?

http://shbox.com/1/4th_gen_tech2.html#ect

 

I had a bad wire on my cyl head temp sensor. The wire insulation was connected with the conductor broke. I tested the resistance with a flame and volt/ ohm meter. Sensor was good. Very difficult to reach down there @ the head left side/ front, so, I moved it. It was broke @ the connector. Rewired/ soldered it. Now it works. B.

 

Yeah mine was broken too. Caused no reading on the dash gauge. ~$25 part.