For information about Si9243 -> VISHAY AN602 "Driver ICs for Automotive Diagnostic Communications Meet ISO 9141 Standards" (->google.com).
Resistor 560R 0,5W is between K-line (6) and Vbat (7) (Si9243AEY) alike 510R between 1 (Vbat) and 4 (ISO) leg of MC33290.
I'd used 560R instead of 510R, because found in few USB-KL-adapters. Sometimes there is adjustment (510R+ potentiometer 0-2000R).
I like it