The blue and yellow wires and sliding jumper are present in the
driver's seat belt and are not present in the passenger's seat belt.
By experiment I found that the warning chime sounds when the jumper
shorts the wires together and is silent when the jumper is moved to
where it no longer shorts the wires together. Snipping one of the
wires silences the chime.
Does it also affect operation of the air bag system or seat belt
pretensioner? Only Hyundai knows for certain. I surmise that it
doesn't for these reasons:
There are air bags on both sides of the car, but the blue and yellow
wires are only on the driver side.
There is another pair of wires going to some sort of sensor in the seat
belt buckle, and this is on both passenger and driver sides. My
deduction is that that sensor is tied into the safety systems, and the
seat belt warning chime uses a separate sensing mechanism because the
safety regulators expect people to try to disable it and don't want the
operation of the air bag system to be affected when they do so. But
that's just my deduction.
If the air bag system did rely on the blue and yellow wires, snipping
them would cause it to act as if the seat belt was fastened even if it
was not fastened. The air bag system might be designed to deploy more
slowly if the seat belt is fastened. If your seat belt is unfastened
when the air bag deploys, causing it to falsely detect that your seat
belt is fastened could give you less protection.
Incidentally, I asked a Hyundai dealer to silence the chime for me. He
refused, saying it was "safety equipment" and it was "not possible".
If you want to silence that annoying chime, you'll have to do it