The back-up light and neutral position switches are combined into one switch with dual functions, often called the PNP switch. To test it, first disconnect the electrical connector for the switch. The back-up light switch should show continuity in Reverse and be open in neutral between terminals 1 and 2, while the neutral position switch should show continuity in Neutral and be open in reverse between terminals 2 and 3. If the continuity does not match these specifications, the switch needs to be replaced. When replacing, be cautious as transaxle fluid may drain depending on the switch's location relative to the fluid level; have a drain pan ready. Begin by raising the vehicle and securely supporting it on jackstands, then disconnect the electrical connector from the switch. Unscrew the switch to remove it from the transaxle, apply a light coat of clean oil to a new O-ring, install the switch, and tighten it securely. Complete the installation by reversing the removal steps and topping off the transaxle fluid as necessary.