Rear Seat Belt LEDs not on

[Michael3295]

I have a 2016 Yaris and i noticed that the rear seat belt LEDs are not on. Im not sure but shouldn't they be on and turn off when the seat belt in in .  Can someone help please ?

[Cyker]

They will only turn on if there's someone sitting there without their seatbelt on, if you're talking about what I think you'r talking about...!

[MikeSh]

I think they also depend on if a back door has been opened.

[CPN]

No. It's much simpler than that. There is a weight sensor in the seat (where your bottom sits) and if something is there weighing above a certain weight that is human like and the seat belt tongue is not in its receptacle (open circuit indication for its switch) then the warning light will come on and stay on until the seat belt tongue is clipped into its other half. I use the phrase "weighing above a certain weight" because it is quite possible to put a heavy shopping bag (8 large bottles of coke for example) on any of the rear seats and the car will think that there is a human sat there...

[bathtub tom]

Get someone (heavy?) to sit on the back seat and see if they light up when you turn the ignition on.

[Starensis]

Does system not run through a start up check and illuminate all 3 lights, then go out if no one sitting in rear?

[Guest]

23 minutes ago, Starensis said:

Does system not run through a start up check and illuminate all 3 lights, then go out if no one sitting in rear?

Not paid that much attention, but I think that's what happens in mine. I also keep the outer belts "clicked" in place when the rear seats are unoccupied. However, not the centre belt and I think the centre l.e.d. does remain illuminated.

[MikeSh]

I've just done a couple of tests on my 2018.

If I just get in alone, start and drive the rear belt lights don't illuminate. Ditto with a front seat passenger.

If I open and close a back door before getting in and driving the three lights come on and go off after a while. (About a minute perhaps but may depend on when the car starts moving too.)

Doing up a belt turns out the light for that seat. There doesn't seem to be any weight detection, but I'd probably need a passenger in the back to take their belt off during a journey to check that.

[Guest]

As I wrote, Mike, not really paid much attention to them. Without actually confirming, I'm almost certain all three light, in my car, by just entering through the driver's door and starting the machine. It's not often I'm right and probably wrong again!

This doesn't explain fully about the three lights either.

"Passenger detection sensor and passenger seat belt reminder
 If luggage is placed on a passenger seat, the passenger detection sensor
may cause the warning light to flash even if a passenger is not sitting in
the seat.
 If a cushion is placed on the seat, the sensor may not detect a passen-
ger, and the warning light may not operate properly"

[preperationlaunch]

There's no weight sensor in the passenger seats in the rear, only in the front.

In the mk3 Yaris, the logic is fairly simple.

When you turn the car on, all 3 lights light up, to show you no belts are buckled.

If you buckle up a seatbelt, the car assumes someone is sat there and the light for that seat goes out. Shortly after, the others also go out.

If a buckled seatbelt is unbuckled whilst driving, then the light comes back on, and possibly it bongs at you. I can't recall.

[flash22]

54 minutes ago, preperationlaunch said:

There's no weight sensor in the passenger seats in the rear, only in the front.

In the mk3 Yaris, the logic is fairly simple.

When you turn the car on, all 3 lights light up, to show you no belts are buckled.

If you buckle up a seatbelt, the car assumes someone is sat there and the light for that seat goes out. Shortly after, the others also go out.

If a buckled seatbelt is unbuckled whilst driving, then the light comes back on, and possibly it bongs at you. I can't recall.

Correct, the audible warning for the belts can be turned on/off In techstream - the fronts have occupancy detection and can detect 4 types of weight, this is for the SRS system

[MikeSh]

1 hour ago, preperationlaunch said:

In the mk3 Yaris, the logic is fairly simple.

When you turn the car on, all 3 lights light up

Not on mine (MK3, hybrid, facelift). Per my earlier post, they only come on if a back door has been used.

[flash22]

Second facelift late 17 on are different due to TSS and the instrument cluster changes

[Cyker]

That's weird, IIRC even my Mk2 would start dinging at me if I put my work back on a back seat and didn't buckle it in.

The Mk4 definitely does!!

[MikeSh]

4 hours ago, Cyker said:

That's weird, IIRC even my Mk2 would start dinging at me if I put my work back on a back seat and didn't buckle it in.

The Mk4 definitely does!!

Just shows how you have to be very specific about which car you are dealing with. This sort of detail can change with a software update these days.

[Guest]

16 hours ago, preperationlaunch said:

There's no weight sensor in the passenger seats in the rear, only in the front.

Which makes the below incorrect? " a passenger seat" which would indicate to me, any passenger seat, front and rear?

That's from the owner's manual.

 

19 hours ago, mrpj1 said:

If luggage is placed on a passenger seat, the passenger detection sensor
may cause the warning light to flash even if a passenger is not sitting in
the seat.

 

[MikeSh]

29 minutes ago, mrpj1 said:

" a passenger seat" which would indicate to me, any passenger seat, front and rear?

It's suitably vague.

Owner's manuals seem to be doing this more and more, though I suspect it's more that they aren't putting the time and money into them to get it clear and correct rather than any deliberate ploy.

[flash22]

It depends on the context and the other text in the article

 

 

[CPN]

22 hours ago, MikeSh said:

Not on mine (MK3, hybrid, facelift). Per my earlier post, they only come on if a back door has been used.

I have now owned 3 Yaris Hybrid models since 2014 (Oct of that year, March 2017 (both Mk3s) and my current Launch Edition Mk4). ALL of them behave(d) in exactly the same way when placing heavy objects on any of the rear seats in relation to the Seat Belt Warning Lights. I stand by my original post. Both the Mk3 & the Mk4 models do have weight (or passenger if you like) sensors integrated into the lower seat cushioning.

[flash22]

2 minutes ago, CPN said:

I have now owned 3 Yaris Hybrid models since 2014 (Oct of that year, March 2017 (both Mk3s) and my current Launch Edition Mk4). ALL of them behave(d) in exactly the same way when placing heavy objects on any of the rear seats in relation to the Seat Belt Warning Lights. I stand by my original post. Both the Mk3 & the Mk4 models do have weight (or passenger if you like) sensors integrated into the lower seat cushioning.

Only in the front seats, it's just buckle switches in the rear unless there bluetooth pressure sensors as the rear lower squib has no wiring - let me see if i can find some srs info

[CPN]

13 minutes ago, flash22 said:

Only in the front seats, it's just buckle switches in the rear unless there Bluetooth pressure sensors as the rear lower squib has no wiring - let me see if i can find some srs info

Then all I can suggest is that my two Mk3s were unique! In both cases, placing something very heavy on any of the rear seats (in my case it was several 24 can cases of Coke because there wasn't enough room in the boot) without connecting the seat belt buckles for that seat, always brought up the seat belt warning light for that seat. How would that happen without a sensor??!

[CPN]

Also see this topic... (not specifically Yaris but I doubt Toyota differ the way they do it across model ranges)

[flash22]

As above if either rear door is opened it assumes a passenger is getting in/out it detects the seat belt buckle open/closed, if the seatbelt is removed above 12mph the alarm sounds if it does not detect the seat belt buckle above 12 mph it ignores it

so there is no rear weight detection

2014 onwards, Inspect rear seat belt warning lights

 

1. Turn the ignition switch to ON (IG).

2. When a rear door is opened and closed (the rear door courtesy light switch turns on and off), check that the rear seat belt warning light in the telltale light assembly turns on.

3. When a rear door is opened and closed (the rear door courtesy light switch turns on and off) and a rear seat belt is fastened or unfastened, check that the rear seat belt warning light in the telltale light assembly changes to inform the driver of the current rear seat belt condition.

   Quote

    

   Rear seat belt warning light

   1. When a rear door is opened and closed (the rear door courtesy light switch turns on and off) with the ignition switch ON (IG), or when the ignition switch is turned from off to ON (IG), the rear seat belt warning light in the telltale light assembly turns on to inform the driver of the rear seat belt condition. The combination meter assembly detects the rear seat belt status and sends signals to the telltale light assembly.

    

[CPN]

1 hour ago, flash22 said:

As above if either rear door is opened it assumes a passenger is getting in/out it detects the seat belt buckle open/closed, if the seatbelt is removed above 12mph the alarm sounds if it does not detect the seat belt buckle above 12 mph it ignores it

so there is no rear weight detection

Ok, I get what you are saying but how does this work then? Let's say I approach the car and open the driver's door (before starting the car) and then, I open the driver's side rear door - wait a few seconds and then close it again. Now I get into the driver's seat, close the driver's door and depress the start button to "Ready"? You would expect a seatbelt light for the offside rear seat to light up (once moving), yes? It doesn't do that.

Here's a couple of photos just now focusing of what happens when you just shutdown at a standstill with something on the back seat... (with the rear seat warning system switched on in the car settings)

 this is what caused it... 

It even detected this light load (and that door hadn't even been opened)

 this is what caused it... 

????

(I should have of course added, that with nothing on the rear seats, that "Attention: Check Rear Seat" does not come up at all (obviously).

PS. No seat belt buckles were (harmed) opened or closed during this test!

 

[Starensis]

Weird. I had the “check rear seat” warning coming up every time I powered off, with nothing on rear seats. I went into settings and deactivated the warning.

I thought it was just a standard message/reminder - regardless.