WARNING: This page is about a different car, the 1994 Acura NSX and 1993 Acura NSX. However, it is still accessible from the selected car via links, so may be relevant.
This signals the ECM when the transmission is in Neutral or Park. See Fig 1
and Fig 2
.
Fig 1: Automatic Transaxle (A/T) Gear Position Signal Diagnostic Flowchart (1 Of 2)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig 2: Automatic Transaxle (A/T) Gear Position Signal Diagnostic Flowchart (2 Of 2)