* Faulty Neutral Safety Switch: This is the most common culprit. The switch itself might be failing, making intermittent contact. Sometimes it works, sometimes it doesn't.
* Wiring Issues: Worn, corroded, or damaged wiring to the neutral safety switch can interrupt the electrical signal needed to start the engine. This can also lead to intermittent starting problems.
* Shift Linkage Problems: If the linkage connecting the gear selector to the transmission is loose, bent, or otherwise malfunctioning, it might not be accurately signaling the transmission's position to the neutral safety switch. This could result in the switch incorrectly reporting that the car isn't in neutral, even when it is.
* Transmission Problems (Less Likely): While less probable, severe transmission problems could theoretically affect the switch's ability to function correctly. This would usually be accompanied by other transmission issues like difficulty shifting.
* Low Battery Voltage (Contributing Factor): A weak battery can sometimes exacerbate these issues. A slightly faulty neutral safety switch might function reliably with a strong battery but fail intermittently with a low battery.
What to do:
1. Check the Battery: Make sure your battery is properly charged and the terminals are clean and tight.
2. Inspect the Neutral Safety Switch: Locate the switch (usually on the transmission) and visually inspect it for damage. It might be accessible from under the hood or from underneath the car. This requires some mechanical knowledge.
3. Test the Neutral Safety Switch (Advanced): This typically involves using a multimeter to test the continuity of the switch in different gear positions. This requires more electrical knowledge and a multimeter.
4. Check the Wiring: Inspect the wiring connected to the neutral safety switch for any signs of damage, corrosion, or loose connections.
5. Check the Shift Linkage: Carefully inspect the linkage to ensure it's properly adjusted and functioning correctly.
If you're not comfortable performing these checks yourself, it's best to take your car to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately and repair it safely. Continuing to drive with this issue could potentially leave you stranded.
