Frontier 2WD V6-3.3L (VG33E) (2003)
Neutral Safety Switch: Description and Operation
PNP SWITCH
When the gear position is P (A/T models only) or N, park/neutral position (PNP) switch is ON.
ECM detects the position because the continuity of the line (the ON signal) exists.
For A/T models, the park/neutral position (PNP) switch assembly also includes a transmission range switch to detect selector lever position.