IS350TP

I blew my stock subwoofer (non ML) and decided to unplug the connector to the subwoofer since I didn't want to spend over $200 on an OEM replacement. Two weeks went by and my car started to die while I was on the freeway. The battery light came on the dash, then a check VSC, traction control, parking brake, abs, and check engine light came on. Then all the electronics in the car started flickering and shortly after my headlights started doing the same thing. Luckily I was able to get off the freeway and park in a nearby parking lot. I had an OBDII reader with me and it threw a P0340, P0345, P0365, and P0390 code which are camshaft positioning sensors. After waiting for 4 hours to get a 27 mile tow, I started thinking about all of the symptoms and it seems like it would be an issue with the alternator. I had AAA come out the next day to check my battery and they said it was low. They jumped my car and it started right away without any issues. I unplugged the positive terminal off of the battery and my car eventually died, this is what confirmed my assumption about the alternator finally dying after 140k miles.

My question to you guys is if you think I diagnosed this correctly and if you think me unplugging the connector to the subwoofer played any part in killing my alternator. I don't see why it would but it seems like these cars are very sensitive to the smallest things. I have already ordered a refurbished OEM alternator from Longo Lexus (which was the cheapest OEM option by far).

LeX2K

Don't see how, your alternator just wore out. Low voltage can cause your codes (sometimes there are way more) the computer starts to glitch out.

mandyfig

Possible that you created a short, meaning your power wires touched a ground.