TC and CG Terminal Circuit: Description
WARNING: This page is about a different car, the 2007 Lexus SC 430. 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 stays blinking, terminal TC of the DLC3 or an ECU may have a ground short.