Overdrive Switch
WARNING: This page is about a different car, the 2002 Nissan Sentra, 2002 Infiniti G20, 2001 Nissan Sentra, and 2001 Infiniti G20. However, it is still accessible from the selected car via links, so may be relevant.
Overdrive switch sends signal to TCM, preventing transaxle from shifting into 4th (overdrive) gear.