2003 sonata alarm issue

My son lost the only key fob to his 03 Sonata (we bought it used). He last locked it with the fob. The dealer had a key that works but because the alarm system is engaged, the alarm goes off and we can't start the car. Is there anyway to disable the system so we can use the key only (and not spend $$$ for a new fob). Thanks.

 

Dealer holding your car hostage for the proper key fob?
How much is the ransom?

 

for the 2003, insert the key in the ignition (well I know the alarm sound is horrible) turn the key to on, wait 30 sec and the anti theft system should cut out. The to prevent this occurs again, look in your car manual, it should mention it.
very easy, unlock the door with your remote, open the hood, find the switch that tell the car the hood is open (located on right side, beside the power steering reservoir).
cut the wire (it is a one wire switch) and ground that wire to the closest body screw. So the computer will think the hood is open and the anti-theft alarm will stay off. I have done this with an elantra 2003 and a 2004

 

oups sorry the text is not clear
for the 2003, insert the key in the ignition (well I know the alarm sound is horrible) turn the ignition to on, wait 30 sec and the anti theft system should cut out. Look in your car manual, it should mention it.
To permanently make sure the anti theft not come back, after the car can be start, leave the key in the ignition, open the hood, find the switch that tell the car that the hood is open (for an elantra, it is located on right side, beside the power steering reservoir, but for sonata I do not know ).
cut the wire (it is a one wire switch) and ground that wire to the closest body screw. So the computer will think the hood is open and the anti-theft alarm will stay off. I have done this with an elantra 2003 and a 2004