Removing Rear Seatback(s)

The illustrated removal procedure is in the Repair Manual (more info). You have to disconnect the rear center seat outer belt assembly (Toyota’s name for the seat belt for the middle seat), and then for the LH and RH seatback assemblies, you can disengage two fasteners on the back at the bottom corners, remove two bolts, and disengage two guides. There aren’t any electrical connectors involved.

The Manual says to wear gloves because of sharp edges. When reinstalling, be sure to use a torque wrench to tighten the bolts, since the torque specification for the bolts (36.8 N·m) is printed in a double box, indicating its importance for safety.

Parts catalog reference: Figure 71-02, Rear Seat & Seat Track.

 

Thanks - can I assume my suspicion that there isn't a sensor on each rear seatbelt, but that the warning light is only triggered by the door?

 

There must be a sensor in each seatbelt in the UK, because I get individual warning lights displayed for my rear seats, depending which belts are being used. They both have child seats in them, but only the right one uses the belt (the other uses the ISOFIX anchors and has its own 5 point harness), so I always get at least the left one displayed. I'm not sure it's the door that triggers it as they always seem to come on even if it's just me in the car. I thought it was the weight on the seat? It definitely is on the front seat as whenever I put heavy items in it the car beeps at me incessantly.

The warning light being displayed incorrectly in such situations annoys some people, so you can get seatbelt "keys" (basically just the metal bit of the clip) from Amazon, specifically designed to clip into the seatbelt connector and hence turn the warning off for that seat. These would work for you if the light bothers you. Although the rear seatbelt warning lights do turn off after a short time anyway.

If you go down this route, be aware that there are more expensive metal keys and cheap plastic keys. Some cars detect the presence of the seatbelt clip by electricity conducting through it so need a metal one, but others use a switch mechanism. Also plastic is more likely to break. If you have access to a 3D printer, there are free designs for these on sites like Thingyverse.

 

The rear seat belt warning lights are triggered by opening the rear doors. The simplest solution to keep the belt lights from coming on is just plug the belts in permanently. The rear belt warning lights go off after a while anyway, so if keeping the belts plugged in is not convenient, no problem.

 

Just tested this, and you're right. No alert is displayed unless you open the rear door(s). The seats do have a sensor in them as then only seats that have some weight on them displays a warning, until the relevent belt is fastened, or a short time passes.

One thing to be aware of is that you can't keep the centre belt fastened permanently if the seat backs are removed, as the centre belt mechanism is part of the back rest.

 

Which explains why, when I put my music case on the back floor, the back seatbelt warnings are shining (all 3) when I start the car. It realises I've opened the door.

 

(from a 2020/21 Prime, but I believe the same info applies)
Sorry no pics, but info for others who might do this:

• 14mm socket (I needed a breaker bar for these) and 12mm (if you're removing the side brackets - recommended to prevent snagging) Also the center bracket has two 14mm bolts and holds an electric connection that is easy to release from the bracket from the rear - pinch the sides in, small flathead works well.
• Flip the seats down and you'll find the 14mm bolts easily.
• To remove the center belt anchor, take a thin/small flathead and look under the bottom seat cushion for a red slot release - push in on it and the middle anchor will release, letting you remove the seat. I did this after removing the seatback and then exploring what else needed to be released for removal.
• It's all pretty self-explanatory and simple to do. Label parts to be safe you remember where they go for reassembly and reverse the order of removal.

Gained cargo space and removed ~30lbs - win, win!

I might remove the seat bottom next and put wood or plastic over the exposed area to ensure no issues with airflow, vs using a moving blanket to pad the area, to gain more height/room.
This will allow us to take the Prime on camping trips where we don't need to full cargo capacity of my VW wagon. (rock climbing and camping gear adds up quickly)