Hello everyone,

Someone I know has a Lexus LS430 that has a problem where after the vehicle is shut off the head unit remains on and stays on to the point that the battery is completely discharged. The battery has been replaced a few times and I'm sure the ECU reset has been performed. I found a thread about this in the forum but it didn't lead to a solution. I'm wondering if pulling the fuse to the head unit and replacing it will make a difference but I don't think it would. Could this be a software issue and not a hardware issue?

 

Odd problem. May be wiring at the head unit. Has it ever been modified or removed? Any add on's? Do other accessories work with the car off?

 

I'm not sure of the answer to any of your questions. I wasn't told that much about the problem and the vehicle in general. The Mercedes Benz S430 has a common problem where the drains at the hood of the car would get clogged with leaves and other debris to the point where the water would back up and go into the cabin destroying electronics. I don't know if that could have happened in this case or if a rodent chewed on the wiring harness. Are there software updates for the LS430 head unit?

 

It's a hardware / wiring issue not software. Show your friend the parasitic draw video.

 

Sounds like a common symptom that happens often when installing a new radio and the 12v 'always hot' gets connected incorrectly with the 12v 'acc'. Since the LS430 head unit is plug and play that should rule that out.
Is the radio staying in standby mode? Perhaps a bad module.

Reccomend to your friend that he install a battery disconnect for whenever vehicle is not going to be operated for extended periods, until he finds the corrective action for fault. Harbor freight has some cheap disconnects for $5 - $6 ... Install to negative terminal, see video below

 

Nice videos