I was driving and radio light started fading on and off, then noticed headlight was out, then radar detector said low volt. 5 min later while driving, power to car cuts off so I'm driving at 10pm with no lights interior or exterior of car for like 15 seconds then lights come back on and luckily i was about where I was going. Parked car to look and headlight works again... with my other SC last year I had similar issue with low volt and ended up having to replace battery and alternator. Is this a common SC problem?! Also I have subwoofers and HID kit if it helps determine issue..

2 days later: Yesterday the car drove fine no issues. However today I was leaving gf apartment and i plugged in radar detector and played music not that loud and car instantly shut off. This time when i tried to crank it back on it wouldnt turn on. Then it made this weird like whirring or whiny sound for a second then car turned back on but this time i had to crank it to turn on. I drove it home with no radio or radar detector and car made it home fine. Does anyone know what in the hell could be causing this? I really dont want to take to Lexus dealership and get wallet raped just for a diagnostic test.

I have a 2000 SC300 with HID kit and 2 12" Subwoofers. Maybe lights or sound system is causing all this???

 

Check your volts on the alternator while running, also check the volts on the battery. Then check the power to and gorund to the alternator.

 

I had my mechanic friend come by yesterday and he said battery and alternator are both working fine when he tested them.

 

Check the grounds from battery and block and see it is loose or corroded.

 

any updates? I am having similar problem

 

If your battery and alternator are fine then you should check your ground wires. I had similar problems as well but added extra ground wires and the problem hasn't occurred since.