TC 30 due to my lack of tech savy I cant post a link but there was a similar thread in 2017 started by ksshooter, and another member duckfarmer27 said he tested his by the manual. You can search this. I would get a work shop manual or see if the dealer will give you the test procedure.
I called the dealer today, asking how to test it, and he said he would look it up. Called back within the hour and said there are no procedures for the later models (after 04 I think he said) mine is an 06. It does look like it is the controller, $355. I asked how they would trouble shoot my tractor and he said he would plug in a new module. I asked what he would do if that didnt fix it and he said put it back on the shelf. But if I buy one, I cannot return it if it does not fix it.