Is there a way to turn off the beeping noise that happens when the seat belt is not buckled on a 2007 Tundra?

First... You should have your passengers wear the seat belts but if you insist you can find the wire going to the seat belt buckle and unplug it under the seat.

check at the base of the buckle where it meets the floor and check the electrical connector there is a switch inside the buckle also check to see if the wire has rubbed against the track

You will have to be a little more specifc please. Do you see the seat belt light on the dash come on at the same time? wiggle the seat belt buckle while you are driving and see if it makes any noise.

hi.
i think your dealership is lying to you.
the warning should not sound if your belt is done up. there IS a problem somewhere.

the first thing to try, is make sure there is nothing left on any seats, and then to buckle up ALL of the seat belts, as it may be a sensor on one of the other seats telling the car that someone is in a different seat.

if this stops the warning, then undo the seatbelts one at a time until on of them sets the alarm off.
this will tell you which seat has a problem.

then go back to the dealer and tell them which seat is causing the problem..
if they still insist there is no problem, ask for the manager and explain exactly what is happening

Find and disconnect the seat belt buckle connector. short the two wires together on the harness side with a paper clip. If the chime/buzzer quits, the problem is in the buckle assembly. If the chime/buzzer is still going off, the problem is some where in the wiring or module.

make sure you are using the right one

Electrical short - probably

You can normally unplug the sensor that is on the floor under the seat, either attached or close to seatbelt.

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http://www.nucow.com/buckle/bucklepup.html