How to service a Neutral Safety Switch
In this post, I detail the procedure for servicing a neutral safety switch aka transmission range switch on the 7th generation Accord. The procedure is similar on Honda and many makes. Does your car refuse to start in Park but starts in Neutral? If yes, the neutral safety switch is the likely culprit. Before replacing parts, its good practice to rule out poor electrical contact, as that can trigger virtually any code in the modern-day car.
Many car owners incur unnecessary costs by simply replacing a part because a code was triggered. A code simply means there is a defection in the electrical circuit for the part in question. Enough said! The neutral safety switch is responsible for telling the ECU the gear position and ensures that an automatic transmission only starts in Park or Neutral positions. Now to business!
- Size 10 mm wrench
- Support stands
- Philips screwdriver
- Electric contact cleaner
- Silicone grease
- Old toothbrush
Part A: Removing the neutral safety switch
- Prepare the vehicle: Turn the key to the “ON” position and move the shifter to the neutral position. Return the key to the position just before “ON” (NB: you will not be able to remove the key from the ignition. This is fine). Set the parking brake. Block the wheels and place the front driver side on jack stands. Remove the driver side wheel. Once removed, you will have access to the neutral safety switch. On some makes, the switch will be on the passenger side.
2. Remove the external cover for the neutral safety switch: This held by 3 size 10 mm bolts. The top and rear bolts are the same length, while the rear bolt is long.
3. Detach the electrical connector: Depress the tab on the electrical connector and remove the connector. For clearance, on this model, you will need to slacken the 2 bolts holding the switch.
4. Remove the switch: This is held by 2 size 10 mm bolts (You may have already started this from the step above). Once the bolts are removed, pull the switch out. Ensure you do not move the gear out of neutral once the switch is removed.
Part B: Servicing the neutral safety switch
5. Disassemble the switch: It is held by 6-philip screws. Ensure you use the appropriate size screwdriver to prevent stripping the heads. Uncover the switch.
6. Clean the contact points and prongs of the neutral safety switch: Use a toothbrush and electric contact cleaner to brush off gunk and old grease. Do not use carb cleaner as it can damage contact points, and degrade rubber and plastic. It is best to remove the rubber seal before spraying with contact cleaner. In the 1st picture, the red line highlights the gunk before cleaning started.
7. Lube up: Using grease with good dielectric property (e.g. silicone grease) lube the following parts of the switch. Avoid the use of regular petroleum grease because it will degrade plastic over time. Also lubricate the rubber seal for proper sealing against moisture.
8. Reassemble switch and refit: Reassemble the switch and mount on the shaft. Other steps are in reverse order. Before torquing the bolts for the switch, reconnect the electrical connector, turn the ignition on and check that the gear positions are correctly illuminated on the dashboard. Finally, torque all bolts to 12Nm and you are good!