* Starter Solenoid: Even if the starter motor itself is good, the solenoid (the part that engages the starter gear) might be faulty. It could be internally shorted, or the contacts might be worn or dirty, preventing it from engaging the starter motor gear. This is a common cause of no-crank situations.
* Starter Motor Issues (despite removal): While you've removed the starter, there could still be internal problems *within* the starter motor that weren't apparent during a cursory examination. Worn brushes, a bad field coil, or a damaged armature are all possibilities. It's possible to test the starter motor with a multimeter or by having it tested at an auto parts store.
* Ignition Switch: The ignition switch might be faulty and not sending the correct signal to engage the starter solenoid. This is less likely if all other electrical systems work, but it's a possibility.
* Neutral Safety Switch: (Automatic transmission) This switch prevents the engine from starting unless the transmission is in Park or Neutral. If it's malfunctioning, it won't allow the starter circuit to complete. Manual transmission cars have similar switches that may need to be engaged correctly.
* Wiring Issues: Check all the wiring between the battery, ignition switch, neutral safety switch (if applicable), and the starter solenoid. Look for broken wires, corroded connections, loose terminals, or damaged insulation. A broken wire anywhere in the circuit would prevent the starter from operating.
* Battery Cables: Though you said electrical components work, ensure your battery cables are properly connected and free from corrosion at both the battery and the starter connections (even though the starter is out). A poor connection can cause insufficient power to reach the solenoid.
* Low Battery Voltage: While unlikely if other electrical components work, a very low battery voltage might not provide enough power to engage the solenoid or starter motor. Test the battery voltage.
Troubleshooting Steps:
1. Visually inspect all wiring: Carefully examine the wiring harness related to the starter and solenoid for any signs of damage.
2. Test the battery voltage: Use a multimeter to ensure you have a sufficient charge.
3. Test the starter (if you haven't already): Have an auto parts store test the removed starter.
4. Check the starter solenoid: This is often the easiest component to test with a multimeter.
5. Inspect the neutral safety switch (if applicable): Make sure the transmission is in Park (automatic) or neutral. Test the switch with a multimeter according to your vehicle's wiring diagram.
6. Check the ignition switch: This is usually more complex to test and might require specialized tools.
Without a proper diagnosis, replacing parts randomly is inefficient and expensive. Starting with a visual inspection and some basic electrical checks is always the best approach before replacing parts. If you are not comfortable with automotive electrical systems, it's advisable to take the car to a qualified mechanic for diagnosis and repair.
