Park/Neutral (P/N) Switch

Unplug P/N switch connector, located near battery. Check for continuity between terminals "A" (Black/White wire) and "B" (Red/Yellow/Black wire). See Fig 1 and Fig 2 .
Continuity should exist between terminals in Park and Neutral. Continuity should not exist in all other selector lever positions. Wiggle wires on selector lever when in "D" position to verify switch is adjusted properly and no short exists.

CAUTION: If vehicle is operated with P/N switch disconnected, idle quality will be affected and a false diagnostic Code 24 may be set.

Fig 1: P/N Switch Circuit ID

Courtesy of GENERAL MOTORS CORP.

Fig 2: P/N Switch Circuit Flow Chart

Courtesy of GENERAL MOTORS CORP.