2000 Hyundai tiburon all lights flash when turn

Unfortunately you need a new bcm, the car will have to go to the dealer. Replacement bcm and reprogram your immobilizer and remotes

need alternator.... perhaps? or most likely a blown fuse...which is an inexpensive fix

replace the turn signal 'Clicker' also known as the turn signal relay. Most likely the problem unless you have a really wierd electical issue that will be hard to isolate...

Peace,

Look closely at bulbs and GROUNDS. Sounds like a running light current is crossing to the T/S circuit.

Its the BCM. Follow these instructions for a cheaper fix.
DIY: BCM Turn Signal Fix - NewTiburon.com

I am guessing, the front from underneath, the back from in the trunk.

Bad news, it's your interior relay-fuse controler..... 800$ canadian money installation included at your dealer. I had this bug late
April this year.
I saw the tech change mine, it's so stupid to install, maybe you can buy it and install it your self

The tiburon turn signals are controlled by a bcm (body control module) The bcm controls the ground to the signals. These always go bad and cause the signal to stick on or just not work. hope i was a help.

I just found out today that it is a problem for alot of 2003 tiburons that the flasher relay for the turn signals will go out causing the turn signal lights to stay on even with the car off. The relays are internal and located on the circuit board of the BCM. In order to fix you will have to remove and disassemble the bcm circuit board from it's housing and resolder a new flasher relay. Haven't figured out where to get that flasher relay though.

Bad news, it's your interior relay-fuse controler..... 800$ canadian money installation included at your dealer. I had this bug late
April this year.
I saw the tech change mine, it's so stupid to install, maybe you can buy it and install it your self