One last question. Could I plug a wire into the female plug to induce a 0 while the car is running to check if it is the TVS or ICU? I am not 100% sure about my ability to use a DMM.

If I use a wire to connect the middle socket to the one away from CSI, I should fool the ICU into a idle signal. If the idle remain high, then I need to order and ICU plus TVS. If teh idle went down, then all I need is the TVS.