Transmission temp gauge

Are sure the transmission is not low on lubricant? And, just as important is the correct lubricant in the transmission? Is there a ‘transmission cooler’?

 

Maybe it's getting very hot?

 

Bottom out? Is that zero or in the red?

 

Most times when one’s hot you can smell it. A faint oil smell. Worse case fall under there and see if you can touch it. My money is on you cant

 

If by pegged you mean it went to the 6 o'clock position then I believe you've got a CAN issue. I seem to recall the gauges do that on Internationals when they have a CAN communication problem.

 

This is a basic hardwired sensor with a manual trans. Remove the cluster, and look for wire A31, 18 gauge grey wire. This eventually goes to the sensor. With the circuit either shorted, or open will cause this. I don't have temp to resistance chart for that sensor, but you can unplug it and measure the resistance it has. Then A31 at the cluster should have that same resistance to ground. If your meter reads OL, then the circuit is open somewhere. If it measures low to no resistance to ground, then it is shorted somewhere.