Dan Ferrell writes on auto maintenance and repair on his own account. It has certifications in automation and control technology.
Is there a problem with your neutral safety switch?
Here are some signs that your vehicle may have a problem with the neutral safety switch.
- Your vehicle starts in a gear other than Park or Neutral.
- The reversing lights do not come on when reversing.
- The gear selection on the dash does not correspond to the actual selection on the gear lever.
- The vehicle only starts in neutral.
- Your vehicle won’t start at all.
In automatic transmissions, the neutral safety switch (also known as the safety start switch) is a switch, normally open, that prevents the starting system from operating while the transmission is running. The vehicle should only be started when the gear selector is in Park or Neutral.
In newer vehicles, this switch also turns the reversing lights on and off and communicates with the car and bodywork computers about the gear position.
On standard or manual transmissions, a clutch safety switch or starter / clutch interlock switch achieves its safety objective by requiring the driver to fully depress the clutch pedal to start the engine.
When the safety switch fails, you can do a series of tests and see if it is just a matter of fit (if it is an adjustable type of switch) or if you really need to replace it. Depending on your particular switch setting, you can test it with a small jumper wire, a test light, or a digital multimeter (DMM).
Just jump to the appropriate section for your vehicle (automatic or manual transmission switches) and start checking your switch.
1. Tools you will need
2. Checking a neutral switch on an automatic transmission
3. Checking a neutral switch on a standard transmission
4. What if my switch works fine?
1. Tools you will need
On a manual transmission:
- Small jumper wire
In an automatic transmission:
- Socket set
- Standard screwdriver
- Phillips screwdriver
- Floor jack (if necessary)
- Two jack stands (if necessary)
- Two wooden blocks (if necessary)
2. Checking a Neutral Safety Switch on an Automatic Transmission
Before trying to adjust the switch, you can do a couple of preliminary tests that can give you a clue as to the condition of the switch. Although it is not a definitive test, it will serve as an additional verification for the procedures that follow:
- step on the brake pedal and hold it there during the test
- Turn the ignition key to the ‘Start’ position (as if you were going to start the engine) and hold it there
- move the gear selector through the different positions
- If the engine starts in a position other than Park or Neutral, the switch most likely needs adjustment.
- If the engine starts only in neutral, the switch probably needs to be replaced.
If the engine does not start in any position, try the following test, first in park and then in neutral:
- place the shift selector in park / neutral
- turn the key to the start position
- move the shift selector without moving it out of Park / Neutral
- If the vehicle does not start, hold the selector forward (only when in park) and try to start the engine.
If you can start or crank the engine, you will probably need to adjust the neutral switch.
Neutral switch location
The neutral safety switch on an automatic transmission (also known as the park / neutral position switch or neutral start switch) is usually mounted to the side of the shift lever (top of the transmission), around the base and near the bottom (front). wheel drive models); other models have the switch attached to the left side of the transmission itself (rear wheel drive). The switch is operated by the shift linkage.
If you don’t know what the neutral switch looks like on your vehicle model, here are three options to find out what you are looking for:
- Consult the service manual for your particular car make and model. Yes…