Mechanics

Neutral Safety Switch Test

AD
Step by step guide on how to test an automotive natural safety switch, this article pertains to most automatic transmission vehicles.

Difficulty Scale: 3 of 10

Step 1 - Identify the neutral safety switch which is located on the left side of the transmission and controls engine starter operation along with reverse lights and gear selection feedback data used by the computer.


Neutral Safety Switch - Wiring Harness Disconnected (Appearance May Vary)

Step 2 - Obtain a wiring diagram used to trace wires which enables continuity testing. This switch uses a simple grounding procedure to individual circuits when the switch is activated. Search Google images or an online service manual such as Mitchell1 to obtain such diagram.


Neutral Safety Switch Wiring Schematic.
 

Step 3 - Using a test light will enable the circuit testing by piercing the wires to confirm a connection through the switch.


Test Light

Helpful Information

The functionality of the neutral safety switch has changed greatly through the automotive development era, what was once a simple switch for the reverse lights and starter safety circuits, this switch has now become a multifunction gear position sensor which provides feedback data to the body and engine computers, all related functions are then carried through the operating system. The neutral safety switch disables the starter operation when the vehicles transmission is not in neutral or park, and are equipped on automatic transmission vehicles only. A standard transmission car utilizes and clutch safety switch in place of the neutral safety switch which accomplishes the same objective. When a neutral safety switch fails it can cause the starter or reverse lights not to operate. Other complications can occur if a loose connection exists near the wiring connector, confirm this connection by removing the connector and reconnecting it.

Tools and Supplies

  • Test Light
  • Wiring schematic
  • Neutral safety switch location (component location)
Tip : If the starter is not working when the vehicle is in park, try pushing down on the brake pedal and putting the transmission in neutral, this will bypass the park circuit of the switch allowing the starter to operate if the park circuit has failed.

Tip: If a neutral safety switch becomes misadjusted, it can cause the switch to malfunction, confirm the adjustment of the switch.

AD

AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


COMMENTS TO THIS ARTICLE


Please use our question form if you have a specific question about your car as we are not able to give you a full answer on this page.



Article first published (Updated 2014-08-08)