What does transmission circuit malfunction mean on a 97 Chevy Tahoe?

Answer 1

The computer controls more and more on the modern vehicles, even the shift point and internal hydraulic pressures.

The code means that the computer has detected a fault in your automatic transmission and that you need to have it checked out.

Typically the code scanners that your local auto parts retailer sells, rents, lends doesn't detect transmission or ABS fault codes. For that you need to either go to a dealer (pay a lot of money) or a transmission shop (be at their mercy and hope you found an honest one.)