You can get a lot of information from (car) Corvette forums which may help narrow down the issue/s. I know various car forums I have subscribed to have helped greatly.
Quick google search I found this Corvette forum and searched P2135 and ran across this one thread. It talks some wiring issues so hopefully previous owners did not do some splicing in of “mods” causing your issue. I am sure there are others.
Code P2135 - CorvetteForum - Chevrolet Corvette Forum Discussion