DTC B1920/77 Short in Rear Driver Side Pretensioner Squib Circuit; DTC B1921/77 Open in Rear Driver Side Pretensioner Squib Circuit; DTC B1922/77 Short to GND in Rear Driver Side Pretensioner Squib Circuit; DTC B1923/77 Short to B+ in Rear Driver Side Pretensioner Squib Circuit: Wiring Diagram
WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.