I just read this thread: http://www.clublexus.com/forums/ls46...ce-or-not.html
I recalled when purchasing my previous ls600hl someone at the dealership told me that the car was able to give power to it's 12v battery in the case that it was depleted, making it virtually impossible to fail to start the car because of low remaining power on the 12V battery. On the thread I quoted it doesn't seem clear as to which of the 12v battery or the hybrid system start the car. From what I read the master technician in that thread said that the 12V wasn't used to start the car but only to power accessories (and maybe act as a relay to start the hybrid system ?). In the thread I quoted, CJITTY described a behavior much alike the one I described in that thread: http://www.clublexus.com/forums/ls46...ft-on-acc.html
My new ls600 is a 2008 and I doubt that the 12v ever been changed. Just recently if I put the car on ACC for more that a minute the car go haywire as described in the thread I created. I'm guessing that the battery need to be replaced. But one interesting thing is that I NEVER failed to start the car, and this happened to me several times. When the car won't start, I just wait a few moment when left in ACC and press the brake for like 10 sec so the green light lit on the start button, and press down (keep pressed) the start button for 5 sec, then release (Sometime I open then close the door before waiting 10 sec then restart the procedure). On the third time the car usually start. So that seems to confirm that the hybrid system might actually give some juice to the 12V battery, or maybe there is a kind of failsafe mechanism that bypass the 12V battery so the hybrid system could start the car ? Would be interesting to know on how exactly the system work when starting the car.