Test B: Scan Tool Does Not Communicate With Class 2 Device: Description
WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
Modules connected to class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Information and commands are exchanged between modules.