Hey Guys, New forum member here. I had all the above issues with my 01 IS200. Lights staying on with key out of ignition, buzzing relay etc. I did have a replacement screen prior to the fault occurring and suspected rain water had got into the fusebox as stated above by several members. However I didn't find any moisture in the fuse boxes.
I work in the motor trade and can get my hands on replacement parts quite easily so I initially I replaced the relay but the new one buzzed also. Next I replaced the light control indicator stalk but sadly the problem remained. Having researched the issue on this forum I noticed lots of people having good results from replacing the anti theft ECU. This worked a treat in my case also and my lights are now fully functional and auto lights are back again. !!! No more inconvenience of pulling the relay out every time to save the battery. Could not be happier with the car now.
Many thanks to everyone sharing their experiences and useful advice on this forum.
TLDR : Anti theft ECU was the problem.
Kind regards,
Scott
