TC and CG Terminal Circuit: Description
WARNING: This page is about a different car, the 2011 Toyota Matrix. However, it is still accessible from the selected car via links, so may be relevant.
Connecting terminals TC and CG of the DLC3 causes the 4WD control ECU to display 2-digit DTCs by flashing the 4WD warning light.
HINT:
When each warning light stays blinking, a ground short in the wiring of terminal TC of the DLC3 or an internal ground short in each ECU is suspected.