Had someone ride in back driver side the other night. She had the belt on while the other two seats were unlocked, which is usually how I keep them. Once in drive and moving down the road, the seat belt alarm started going off, I mean really loud and annoying. Had to pull over and fasten the rear middle belt to silence it. The arm rest was pulled down, too, if that makes any difference. Any others here experience such a problem?
My first guess is that she buckled her belt into the wrong receptacle(middle instead of left). Or maybe the receptacles got flipped during assembly so they're on opposite sides now. You'd need to do some testing to see. Or maybe the weight sensor in the center rear seat was triggered. If she had the armrest down and was leaning on it, maybe? Seems unlikely, but I can't rule it out. (That's assuming the rear seats have air bladder sensors like the front seats do.)
Sometimes when I'm getting groceries, the weight on the passenger seat sets off the seat belt alarm. The easy solution is to buckle the belt.
Yep, you'll need to do some testing - but it's a safety system issue and your probably still under the 3 year 36K mile bumper to bumper warranty. Hope this helps...... FWIW; I had a similar issue in my gen4. Chalked it up to a software glitch because I couldn't reproduce the issue.
Last time I was at the dealer, they criticized my buckling the belt behind me, but they did not threaten any warranty issues.
Interesting. Those last posts made me realize I regularly put groceries in the rear seat but have never had the seat belt alarm go off. Never thought about that before. As a side note, the 2025 Siena is trying out using ultrasonic sensors over the rear seats for occupant detection purposes. They're mostly looking for movement so they can tell the difference between a person/pet and cargo. The sensors are basically the same as the ones Toyota's been using for years in the bumpers, so it's not like they're developing this from scratch or anything. Just using proven tech in a new way.
I've done that myself; buckling to the wrong receptacle, but it still worked nonetheless. Apparently all the buckles were on the same circuit.
I've had occasional rear alarms from bags, but they shouldn't be going off in OP's situation. At least here you can silence the beeps for any of the passenger belt warnings with a scantool, so the rear ones have been silenced. You still get the red lights.
Buckled correctly. It shall remain a mystery until I can test again with passengers, with and without arm rest down. Thanks for input, everyone.
Sounds like I’ll have to buckle up my empty seats. I’m always using the back seats rather than the cargo area for groceries etc. Cargo area will get too hot with this newly designed flimsy cargo cover that doesn’t give much protection. Positives about it are that it’s easier to access. Pulling that cargo cover on my 2009 is often challenging.
I regularly embark on my dog on the back of my Prius Prime and to no longer have a warning when it moves to the back, I deactivate with my scanner OBD2 the sound warning of the 3 rear seats.
