Headlight chime keeps ringing when lights are off

Check the seatbelt system. and sensor in the seat.

when you hear vechicle alarm chime keep ringing.got problem with emergency brakes still applied or headlight switch on in the manual position.

I would start with the fuses first. No I don,t believe they are but reading more into your problem I would check your alternator if not receiving the right amount of amp. output could and will make your computer go crazy. so check that first let me know how it goes good luck.

on some vehicles the chime for the headlights is the same as the chime for the doors, if you have your interior light turned off via switch or just a bad door jamb switch then the headlight chime may not work. at least that's why my dodge quit chiming.

Have you recently replaced any bulbs? Did you use dual element bulbs. It sounds like the wrong bulbs were used and the brakes lights are backfeeding the tail light circuit.

Cold be an electrical break in a wire or relay could be blown.You will have to ckeck everything.

try removing your battery terminals then put it back again to reset the system of your car back to original

Yes, there are aftermarket chimes, and there is also a battery level shutoff, when voltage under 8V is sensed, it will stop the battery from working until you put a key in the ignition.
The IS 300 should have a lights on chime minimally. Is the radio a factory one?

the switch that shuts off the dome light and chime is part of the door latch and is broken