Replace seatbelt sensor - 2001 Lexus RX 300

It sounds like it could be a seat belt sensor. These only work when the car is moving. Do you have anything on the passenger seat that could make the car think there is a passenger there?
Try fastening all the seatbelts and see if the beeping continues. If there is no beeping, try unfastening the seatbelts one by one & see if you can find which one is causing the problem.
if it turns out it is a seatbelt sensor, you could drive with that belt fastened until you can get the sensor replaced.

B stands for Body...Respectively 1881, 1887, and P1xxx is emission system....

B1881 Seatbelt Passenger Pretensioner Circuit Open
B1877 Seatbelt Driver Pretensioner Circuit Open
P1290 Cylinder Head Temp Sensor Low Input

Address the Cylinder Head Temperature sensor, which is reason for running poorly...Replace CHTS...See diagrams...

It requires the removal of the alternator...




remove connector


Remove sensor


Cost around $30

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

If you have a heavy enough object sitting in the passenger seat, the sensor may think a person is sitting there without a seatbelt on....or in a case that I ran into a few years back, a small coin had lodged inside my locking side seat belt. The side with the release button. Or lastly, have you vacuumed your car recently? You may have unplugged your seatbelt sensor wires while vacuuming.
Your car is getting up in age too, so check to see if the retracting spring is still pulling the seatbelt back into its holster, check the general condition of your locks on the belts....not sure if there is a fuse link for a seatbelt system in your car...but you could check your owners manual to see if there is, and while in the manual...check for reasons the seatbelt light comes on too. You can get a copy of your owners manual on line from Nissan or a aftermarket source. Good luck and sorry I couldn't be more specific. Your owners manual or an on line search of the trouble code and the specific working generated by the readout will give some information I'm sure....Work safely please. and beware of air bags when messing with seat safety issues. If you deploy an air bag on yourself while messing with the safety controls.....you could be killed or injured....so be careful.

How many does it make after 10 minutes? Try fastening the seatbelt, or making sure the seatbelt sensor works. Its in the buckle down below the seat. If its unplugged, the seatbelt sensor cannot report that the seatbelt is fastened.

You need to replace the airbag control module, it is a one time use device.

The sensor in the seatbelt is definatly not working, Sounds like an expensive repair for just a chime,
as a joke I would find the chime and unhook it. But seriously you might be able to find the wiring under the seat for the seatbelt and unplug it depending on the year but after 20 minutes of research all seatbelt replacements ive found say they come without electronic sensor anyway.
Good luck and hope I helped you out some....
I tried my best!
Larry

If the seat belt has jammed, you may just need to replace the mechanism- you want it to do its job correctly when you need it
For your information,--You may need to replace the mechanism for the seat belt. If the impact restraint system has encountered what they refer to as a stage one deployment due to a minor accident, the seat belt locks up, and even though the airbag(s) hasn't deployed, there are frame sensors that may need replacing reset.
We encountered this with my daughter's 05 Focus and needed to replace the belt assembly, and a couple sensors on the frame..

sensor in the seat belt bukle needs to be replaced

when airbags deploy there are seatbelt sensors in some vehicles.