To test the automotive neutral safety switch on your car, examine the wiring of the switch, disconnect the switch and the wiring connector, and bring the vehicle's gear into reverse. Then, check if power is supplied to the wiring harness using a test light.
Begin testing the automotive neutral safety switch on your car by locating the switch in the vehicle using the service manual. The switch, which looks like a cigarette lighter, is normally situated close to the shift mechanism. If the car is of the column-shift type, look for the switch on the transmission's side and close to the gear shifter.
Check if the wires of the switch are connected to the starter solenoid. Refer to the switch's wiring schematic detailed in the service manual, and disconnect the switch and its wiring connector.
Now, insert the key in the vehicle's ignition, and set the gear to reverse. Keep the engine switched off. Connect a test light of 12 volts to the wiring harness. If the bulb of the light gets illuminated, it shows that the switch's circuit is functional. In such a case, reconnect the switch and the wiring connector.
If the test light's bulb does not light up, look for loose connections or damaged wiring. Repair any findings, and test the switch again. If power is not present, replace the existing switch.