Rear seatbelt indicator fault

[Kmac888]

2012 mk3 Yaris.

hi everyone I've done a search on this before posting but can't find an answer. 

Problem is I have 3 red lights on the cluster showing that the rear seatbelts are not fastened also the beeping sound is on.....but all 3 seats are unoccupied. If I clip the seatbelts in the light & alarm goes off. 

Is there a way of deactivating this warning or is it a problem with one of the weight sensors under the seat?? 

thanks all

 

 

 

 

[FROSTYBALLS]

Topic moved to the Yaris forum

[Bernard Foy]

The electrical supply to the sensors are under the back seat, if the actual sensors are faulty you can easily disconnect the power supply.

[Kmac888]

so......take the rear seat out and disconnect the sensors ( for the weight detection)?

[flash22]

there is no weight detection on the rear seat just the 3 or 4 belt buckles

it could be just a iffy door switch on the rear doors

[jthspace]

You can also disable the warnings using Carista app and an OBD plug

You can buy a months subscription to turn off back seat warnings, make windows auto-open with long remote press etc etc. Check out their website.  However, if there is a fault, then it would be best to find out whats wrong first.

 

[bathtub tom]

Mine come on for several seconds if a rear door is opened. I presume as a reminder.

[Kmac888]

well......it's fixed!!!! I plugged in and released all three seatbelts several times and now the three red lights on the dashboard module and the beeping has gone. Thanks for all the replies, if it comes back I'll know what to do.....🤔

[Kmac888]

7 hours ago, flash22 said:

there is no weight detection on the rear seat just the 3 or 4 belt buckles

it could be just a iffy door switch on the rear doors

if there is no weight dectector on the rear seat how does the car know someone is sat there without a belt?

[MikeSh]

2 hours ago, Kmac888 said:

if there is no weight dectector on the rear seat how does the car know someone is sat there without a belt?

10 hours ago, flash22 said:

there is no weight detection on the rear seat just the 3 or 4 belt buckles

The belt buckles have detection.

If a rear door has been opened then the car assumes someone may have entered and energises all three lights. If a buckle is done up that light is extinguished. After a delay time all lights are extinguished regardless.

It's a fairly crude system so the driver can see if any passenger isn't buckled in.

[RickyC]

29 minutes ago, MikeSh said:

The belt buckles have detection.

If a rear door has been opened then the car assumes someone may have entered and energises all three lights. If a buckle is done up that light is extinguished. After a delay time all lights are extinguished regardless.

It's a fairly crude system so the driver can see if any passenger isn't buckled in.

Maybe in Mk3.

But in Mk4 the weight sensors are surely present because the lights indicate exacly which seatbelt is not buckled.

If I open a rear door the seatbelt alarm is not triggered unless there's someone seated or someting weighting more than a few kg on the seat.

I remember last Christmas.  I placed a large Christmas Star plant on the rear seat and I started driving without any alarm.   Then i got a road bump and the plant got a jump triggering the alarm.  I had to stop and buckle the seatbelt.

[MikeSh]

2 hours ago, RickyC said:

Maybe in Mk3.

But in Mk4

The OP's profile is for a 2012, so probably not a MK4.

[Kmac888]

5 hours ago, MikeSh said:

The OP's profile is for a 2012, so probably not a MK4.

yes 2012 mk3 Yaris. When the 3 red seatbelt lights and the alarm triggered they stayed on for the entire communte to work (lights on but beeping stopped after a minute) could have been a glitch or something stuck in the seatbelt buckle?

[flash22]

there is no rear seat detection as it's not required as there are no forward-facing airbags in the rear (mk3 and mk4) - the system works off the door switches and the belt buckle switches

I would start by plugging in 1 belt at a time, if the back doors don't get used much give them some exercise, the door switches can go sticky

 

 

[jthspace]

?? Sorry Bob, disagree as if someone sits in the rear of my Yaris then the seatbelt warning light on the dash flashes  door open or closed so it must be detecting a person somehow. If I sit in the back and push myself up, the warning light goes out.  If i press down hard with a fist (on the centre seat) that then lights the warning on the dash - hence I believe there must be some sort of pressure pad.

 

[flash22]

there are no mats or sensors listed in the epc or in the EWD for either the Mk3 or 4 inc the cross

 

it must be some sort of voodoo magic then, i will look up the overview tho

edit.

Front seat inner belt (driver side buckle switch)	Informs main body ECU (multiplex network body ECU) of driver seat belt condition (fastened or unfastened)
Front seat inner belt (front passenger side buckle switch)	Informs combination meter assembly of front passenger seat belt condition (fastened or unfastened)
Occupant detection sensor	Informs combination meter assembly of front passenger seat condition (occupied or unoccupied)
Rear seat inner belt, rear seat inner with center belt	Informs combination meter assembly of rear seat belt condition (fastened or unfastened)
Front seat belt warning light	If driver seat belt is unfastened and ignition switch is ON (IG), combination meter flashes seat belt warning light in combination meter assembly as reminder When front passenger seat is occupied and ignition switch is ON (IG), if front passenger seat belt is unfastened, combination meter flashes seat belt warning light in combination meter assembly as reminder
Rear seat belt warning light	When the rear door is opened and closed (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 combination meter turns on the rear seat belt warning light in the telltale light assembly as a reminder
Seat belt warning buzzer	If the vehicle is driven at approximately 20 km/h (12.5 mph) or more with any of the following conditions met, the combination meter sounds buzzer as a reminder: 1) the driver seat belt is unfastened, 2) the front passenger seat belt is unfastened with front passenger seat occupied, or 3) rear door has been opened and closed and the rear seat belt is unfastened.   Seat belt warning buzzer: The seat belt warning buzzer in the combination meter assembly sounds at an interval of 1.2 seconds for 30 seconds, and then the buzzer sounds at an interval of 0.4 seconds for 90 seconds when the vehicle is driven at approximately 20 km/h (12.5 mph) or more and any of the following conditions are met: 1) the driver seat belt is unfastened, 2) the front passenger seat belt is unfastened with the front passenger seat occupied, or 3) a rear door has been opened and closed and a rear seat belt is unfastened

[flash22]

Just to correct myself the mk4/cross does have occupancy sensors in the rear it's just not listed in any part of the diagrams, the Mk3 what the OP owns does not

video of an old boy struggling 😉

 

[Stevie J]

I've never noticed mine beeping with the rear seat belt lights on, as I often open the rear doors and put bags and umbrellas etc in the rear footwells before driving off so in those circumstances I would have thought the buzzer would sound.

I know it sounds if I dump my bag on the passenger seat and there is a water bottle or something heavy in it - it triggers the over sensitive weight sensor in the seat cushion and makes the car beep at me so I put bags in the front or rear footwell now and avoid putting anything on the front seat. I will make a point of specifically opening and closing rear door before driving away next time and observe the indicators - maybe just the rear seat belt lights come on, but I'm sure it doesnt beep at me, well, it never has in the year I have owned it.