1. Check for continuity between the No. 1 and No. 4 terminals of the transmission gear selection switch/park pin switch connector while pushing the button of the shift lever in, and when released.

Is there continuity when pushing the button in, and no continuity when it's released?

YES | - | Check for an open in the wire between the multiplex integrated control unit and the park pin switch connector. If the wire is OK, replace the multiplex integrated control unit .■
NO | - | Replace the park pin switch .■