I just purchased a 2008 Outlander XLS. The key fob works fine to lock/unlock the doors, but both interior door lock switches do not work at all (no sounds or anything). Is there a way to diagnose which one is causing the problem? Are they connected to each other somehow that if one stops working, the other won't work as well? Any specific part recommendation?

 

easiest thing to start with is fuses and relays - the internal switches are wired to the control module whereas the signal from the fob is sent via network from a different module - just to be sure, I'd also see if the key blade turns the drivers door lock manually (mine did not when needed it to work - likely the result of a theft attempt that pulled the connecting rod off)