On my 2006 Corvette, the Engine, Transmission and Brake functions of the Vehicle Diagnostics does not work.
My dealer called an Onstar Tech and was told there is a Nationwide problem with vehicles that have version 6.11 software . Later version 6.15 software is ok.
Systems were downgraded for battery drain problems.
The Onstar Tech told my dealer that GM is working on a version update for the problem. They will send an over the air download when they get the fix and it is approved by the FCC.

Is that on all 2006 C6's?

They told me that cars with the 6.11 software were affected.
If you sign up for the Onstar remote diagnostics that they send each Month on E-Mail, You will be able to tell because it will not show any information about the Engine,Transmission or Brakes.

Okay, my diagnostics email did list the Engine Tranny and brakes. It says that it checks the following...

The following is a list of most major subsystems monitored through OnStar Vehicle Diagnostics.* The capabilities of OnStar Vehicle Diagnostics and GM® Goodwrench® On Demand Diagnostics vary by make and model.

Emissions Systems
Air Induction System
Fuel Management System
Engine Cooling System
Throttle Control System
Variable Valve Timing System (where applicable)
Ignition System including Misfire Detection
Active Fuel ManagementTM/Displacement on Demand (where applicable)
Engine Electrical System including Voltage and Charging/Starting System
Transmission Control System
Antilock Braking System including related sensors, module, and electronic components
Traction Control System and StabiliTrak® (where applicable)
Supplemental Restraint System including Airbag Deployment Mechanisms and related sensors
OnStar System

Onstar has fixed the problem. They sent out an over the air fix to all vehicles with the problem.They also made some changes at Onstar. Everything works fine now.