Factory trans. Temp. Gauge acting strange

[Boatswain]

I have a 2004 2500 G.M.C. Sierra 4X crew cab. I have noticed lately that my factory transmission temp gauge is not reading right. Sometimes it will peg all the way to the right to 300 degrees and I am not even towing anything or working the transmission hard. When this first happened I checked the engine temp and it was fine and did not climb. The gauge seems to jump from hot to cold and back again. Could it be the sending unit or a bad gauge. If it is the sending unit does anyone know where it is located on the transmission? Has anyone else had this problem. Truck only has 57,000 miles on it. Thanks for the help.

[rapidoxidationman]

Not sure where the sensor is, but if your local parts store can show you one then I bet you can find it on the transmission unless it is internal...

Just curious: Have you checked the fluid level? Is it possible that the level is low or that the cooler air flow is blocked?

[More Power]

A Tech II scan tool and some handheld programmers can be used to read the transmission temperature by communicating directly with the vehicle computers. This would help to identify whether it's the sensor or the gauge.

Jim