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
- 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
online service manual such as
obtain such diagram.
Neutral Safety Switch Wiring Schematic.
- Using a
will enable the circuit testing by piercing the wires to confirm
a connection through the switch.
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 multi-function 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
Tip : If the
starter is not working
- Test Light
- Wiring schematic
- Neutral safety switch location (component location)
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.
If a neutral safety switch becomes maladjusted, it
can cause the switch to malfunction, confirm the adjustment of the switch.
Article first published 2017-01-26