It always amazes me how much I see every day and never pay any attention to until the question comes up. Case in point.
I have an IC that will kill the batteries if not run every couple days. After much testing of electrical circuits and components I think the EGC is staying awake and trying to communicate on the J1939.
The information center in the EGC stays lit up all the time. If I open the j1939 to the engine it goes dark and my amp draw drops by 2/3's.
My question, does the information center ever go dark or does it normally stay lit and display odometer info constantly?
Just out of curiosity what yr IC are you working on? Mine up to 2012 will go to sleep a few sec/min's after shutdown... if I plug in the laptop with or without turning on ignition either way it will wake up.. of course if I want to connect to engine or any other ecm's.. key has to be turned on.. I am taking it by what you posted that if you connect to the engine ecm dash goes to sleep?
Mine normally go dark after a set time...to answer your question...