* Neutral Safety Switch: This switch prevents the vehicle from starting unless it's in Park or Neutral. A faulty switch can fail and prevent the starter from engaging, even if the engine appears to crank. This is a likely culprit because it's related to the starting system rather than the ignition system once running.
* Ignition Switch: The ignition switch itself could be failing. It's responsible for sending power to various components, including the starter. If it fails internally, it can prevent power from reaching the starter motor even though the key is turned to the start position. This is also higher probability than an intermittent engine problem.
* Battery Cables/Connections: Though you mention cranking, corroded or loose battery cables or connections can lead to insufficient power to the starter motor, especially after the engine has been running (heat can exacerbate corrosion issues). Check these meticulously. Even a seemingly good connection might have high resistance.
* Starter Motor Solenoid: This is a part of the starter. The solenoid is responsible for engaging the starter motor. A failing solenoid might click (you may hear a click) when you turn the key, or simply do nothing.
* Main Power Relay: Some vehicles have a main power relay that controls power to various systems, including the ignition and starter. If this relay fails, it can prevent the starter from receiving power.
* Inertia Switch: Some vehicles have an inertia switch (typically found under the dash or in the engine bay) that cuts power to the fuel pump and ignition system in a collision to prevent fires. This might have tripped unintentionally.
Less Likely (but still possible) given your description:
* Intermittent crankshaft position sensor (CKP) or camshaft position sensor (CMP): While these sensors are crucial for engine operation, a problem that completely shuts down the system and *also* stops cranking simultaneously is less likely than the aforementioned issues. They usually cause a no-start *after* the engine has run and cooled down, or an erratic running issue.
* Fuel Pump Relay: Again, if the fuel pump isn't running, the engine will die, but you'd still expect the starter to crank. Your problem is broader than this.
Troubleshooting Steps:
1. Battery Voltage: Test the battery voltage. A weak battery can cause cranking issues.
2. Battery Cables and Connections: Thoroughly inspect all battery cables and connections for corrosion or looseness. Clean and tighten as needed.
3. Neutral Safety Switch: Check to make sure the vehicle is in Park or Neutral. If possible, try starting in the other gear position. A test light can be used to verify this switch is operating correctly.
4. Ignition Switch: This is often the most difficult to test without specialized tools, but if the other possibilities are ruled out, it is likely the culprit.
5. Starter Solenoid: Listen carefully for any clicking sounds when you turn the key. A clicking solenoid often indicates a problem.
6. Inertia Switch: Locate and reset the inertia switch (if equipped).
7. Main Power Relay (If applicable): Check the main power relay.
Important Note: If you're not comfortable working on your vehicle's electrical system, it's best to have a qualified mechanic diagnose and repair the problem. Improperly working with the electrical system can be dangerous.
