TC and CG Terminal Circuit [08/2013 - ]: Description
WARNING: This page is about a different car, the 2014 Lexus ES 300h. 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 dynamic radar cruise control system to enter self-diagnostic mode. If a malfunction is present, the cruise control indicator light will blink.
HINT:
When a particular warning light remains blinking, a ground short in the wiring of terminal TC of the DLC3 or an internal ground short in the relevant ECU is suspected.