I know this is older but.... I’ve had this very same problem on and off also. I’ve also noticed that my driver side and possibly opposite passenger side door switch are bad or defective. What I noticed is that often when I open my driver door (some times the said passenger) the door courtesy light flickers, blinks, or just doesn’t come on at times. Pushing on it and moving it around recreates this effect. Testing this today while holding down the defective door switch by hand and counting down to 60 revealed the possible problem. The headlights did turn off. What I believe is happening is the switch isn’t closing properly making the circuit “think” the door is still open keeping the lights on. This is just a hunch. The dealer trouble shooted this problem before and found nothing. So my guess is it’s either the door switch causing a short or fault. Or the headlight combo switch is bad. Can also be a short somewhere in the lighting circuit. Maybe someone installed an alarm or stereo equipment that’s pinching the wiring.

thanks glad it’s something easy to repair on my own. Will go ahead and get the switches with my next parts order.

I have a older gs430. A 01, but this was happing to me and what I found was the truck had been popped open and I didn't see that. So remember if your truck is open the headlights won't go off till the truck is closed.

Thanks I figured out that any door opened would not allow the lights to shut off. What I learned about my gs is that it has a defective door switch on the driver side. It would even make the alarm/lock malfunction at times. Tested the other 3 one of the rears is also defective. The way to test is with the door open you keep pressing the switch to see if the door courtesy light comes on. The switches would get stuck a few times now and then. Switch no good. The driver door I learned cause after the first week of owner ship I noticed that my door courtesy light would flicker on and off intermittently. Someone has already replied letting me know that this will cause the problem I’m having. I finally ordered new switches. Just waiting for them to arrive. As person another members suggestion. I purchased all 4 switches. Again thank you. And btw I just recently learned that this model year has a warning indicator if u don’t properly latch the hood. I didn’t think it did until the one time I apparently didn’t properly latch the hood. It was late at night and dark so I couldn’t tell.

yes that is correct. Here is a link to the thread of the said job.
https://www.clublexus.com/forums/gs-...with-pics.html