* Starter Motor: Even with a new solenoid, the starter motor itself could be failing intermittently. The internal components (brushes, windings) can wear out and cause a clicking sound but no cranking. This is a common failure point. Testing the starter motor directly (often requiring removal) is the next step. A mechanic with a starter tester can do this easily.
* Ignition Switch: The ignition switch might be failing intermittently, not providing proper power to the starter circuit. This is less likely given you've replaced the solenoid but is still a possibility. Testing the switch for continuity is needed.
* Neutral Safety Switch: This switch prevents the car from starting unless it's in Park (automatic) or Neutral (manual). A faulty switch won't allow the starter circuit to complete. Check that the transmission is definitely in Park or Neutral and that the switch itself isn't malfunctioning. You can test this with a multimeter.
* Wiring and Connections: Inspect all wiring related to the starter motor, solenoid, and ignition switch. Look for corrosion, loose connections, broken wires, or chafing against metal. Pay close attention to the positive cable running from the battery to the starter. A bad connection anywhere in this circuit will prevent cranking.
* Flywheel: Though less common, a damaged flywheel (the part the starter engages) can prevent the engine from turning. This would usually involve more than just clicking, but it's possible for intermittent damage to create this symptom. This requires more advanced diagnostics.
* Low Voltage: Though you replaced the battery, ensure the battery is properly charged and holding a charge. A bad alternator could be the underlying cause, leaving the battery too low to crank consistently. Check the alternator output voltage with a multimeter.
Troubleshooting Steps:
1. Check all connections: Visually inspect every connection in the starting circuit for corrosion, looseness, or damage. Clean and tighten as needed. Pay particular attention to the battery terminals and the large positive cable connection to the starter.
2. Test the battery voltage: With the engine off, check the battery voltage. It should be around 12.6V or higher. Then, try starting the car and check the voltage again. A significant voltage drop indicates a problem with the battery, charging system, or a very high current draw (likely the starter motor).
3. Tap the starter: While someone turns the key to start, gently tap the starter motor with a wrench or hammer (be extremely cautious!). Sometimes a stuck internal component will respond to a slight impact, but this is a temporary fix at best.
4. Seek Professional Help: If you're not comfortable testing the electrical components yourself, take it to a mechanic. They have the tools and expertise to diagnose the problem accurately. Describing the intermittent starting and the clicking sound will help them focus their efforts.
Don't attempt any advanced electrical work if you're not experienced, as this can lead to further damage or injury. Safety first!
