TC and CG Terminal Circuit: Description
WARNING: This page is about a different car, the 2008 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
Connecting terminals TC and CG of the DLC3 enables DTCs to be read through blinking patterns of the combination meter's CRUISE main indicator light.
HINT:
When a warning light of the combination meter blinks continuously, terminal TC of the DLC3 or an ECM may have a ground short.