Circuit Description - DTC P1780 - Information Codes 118, 119, 120, 121: Notes

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

When using an OBD II scan tool other than TOYOTA hand-held tester, check all the steps.
When using TOYOTA hand-held tester, confirm the information code and check it.

The park/neutral position switch sends both main sensor signal (switch signal) and sub sensor signal (analogue value) to the HV ECU. The HV ECU uses those signals to detect the shift lever position (P, R, N, D or B) and to control the forward and backward movement of the vehicle.