Toyota Prius 2010 Repair Manual page 401

INSTALLATION
HINT:
Use the same procedure for the RH side and LH side.
The procedure listed below is for the LH side.
1. INSTALL REAR AIRBAG SENSOR
(a) Check that the power switch is off.
(b) Check that the cable is disconnected from the negative (-) battery terminal.
CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS
system.
(d) Connect the connector to the rear airbag sensor.
NOTICE:
When connecting any airbag connector, take care not to damage the airbag wire harness.
2010 Toyota Prius
(c) Insert the pin (stopper) into the body hole to install the rear airbag
sensor to the vehicle with the nut.
Torque: 9.0 N·m (92 kgf·cm, 80in·lbf)
If the rear airbag sensor has been dropped, or there are any cracks,
dents or other defects in the case or connector, replace it with a new
one.
When installing the rear airbag sensor, be careful that the SRS wiring
does not interfere with or is not pinched between other parts.
Make sure that the pin (stopper) is securely inserted into the body hole.
Tighten the nut while holding the rear airbag sensor because the rear
airbag sensor pin (stopper) is easily damaged.
Repair Manual