You have two operating thermostats located on the front of the blower cover, behind the front panel. One is for high temps, the other for low. I would first check these for continuity
, then if they were good, assume the timer itself is bad
If the unit works on Timed dry but not on Auto dry, these are the 2 choices you have with this model. To access the thermostats, unplug the dryer, pop the main top (4 screws under top egde) and remove 2 screws inside the front panel at the top, then loosen the 2 underneath in front. The whole front will lift off so you can check the thermostats.
In the diagram below, the thermostats are items 274 and 275DIAGRAM (click)