The TC light is on, bought from a dealer and they said it was fixed when I bought it and reset the light. Came back on while I was driving it home. Any idea what the cause of this is and what the fix is?

 

Have the codes read. If light is on, there should be a code.

Or...take it back to the place you bought it from and have them really fix it.

 

The dealer should check it out since you had just bought it.

What year is your Disco? It will be helpful to pic it in the signature of each of your posts.

It could be a stuck diff lock sensor, ie, assuming your have CDL. The sensor is a spring loaded pin mechanism. They have a tendency to get stuck which creates an electrical circuit prompting the diff light indicator to turn on.

 

The CDL light is different from the TC light.

 

Oops, my bad, I was going too quickly. I was thinking in my head it was "Transfer Case". Just realized the OP meant "Traction Control". Sorry for the confusion!