What causes transmission temperature to go up

Make sure the trans level is ok. Also, if you have an external trans cooler make sure it's not dirty or blocked and the engine fan is working ok. Alex

Normal operating temperature for an automatic transmission is about the same as the engine temperature, i.e., about 195°F. The temperature inside the torque converter, while pulling a big load from a standing start, could easily rise above 350°F. Fluid breakdown often results in harsh shifting and slip-bump concerns.