DTC B1920/77: Short in Rear Pretensioner Squib RH Circuit; DTC B1921/77: Open in Rear Pretensioner Squib RH Circuit; DTC B1922/77: Short to GND in Rear Pretensioner Squib RH Circuit; DTC B1923/77: Short to B+ in Rear Pretensioner Squib RH Circuit [08/2013 - ]: Wiring Diagram
WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.