* High Resistance in the Wiring: Even with new components, corrosion or a bad connection in the wiring harness between the battery, solenoid, and starter can cause a significant voltage drop. Inspect all wires and connections carefully. Look for:
* Corrosion: Clean any corrosion you find with a wire brush and battery terminal cleaner. Apply dielectric grease to prevent future corrosion.
* Loose Connections: Ensure all connections are tight and secure.
* Broken Wires: Check the wires for any breaks or damage, especially near bends and flexing points.
* Neutral Safety Switch: This switch prevents the starter from engaging unless the transmission is in Park or Neutral. A faulty neutral safety switch will prevent the starter from receiving power. Test this switch with a multimeter to verify it's working correctly.
* Ignition Switch: A worn or faulty ignition switch can prevent power from reaching the starter solenoid. Testing this requires a bit more electrical knowledge and a wiring diagram for your specific Explorer year.
* Insufficient Battery Power (despite a new battery): While you've replaced the battery, it's possible it's defective or not properly charged. Test the battery voltage under load (while cranking) using a multimeter. It should be above 9.6 volts; significantly lower indicates a battery or charging system problem.
* Ground Connections: Poor ground connections can prevent the proper flow of electricity. Check all ground straps and connections for corrosion and tightness. The engine block ground is particularly crucial.
* Solenoid Power Wire: Ensure the large power wire to the solenoid is securely attached to both the solenoid and the battery's positive terminal. A loose connection here is a common culprit.
Troubleshooting Steps:
1. Visual Inspection: Carefully examine all wiring, connections, and components related to the starting system.
2. Voltage Testing: Use a multimeter to check the voltage at different points in the circuit. Compare the readings to a wiring diagram to identify voltage drops.
3. Ground Check: Use a multimeter to test the resistance of the ground connections. A high resistance indicates a poor ground.
4. Neutral Safety Switch Test: Test the continuity of the neutral safety switch using a multimeter, ensuring your transmission is in park or neutral.
If you're not comfortable working with car electrical systems, it's best to take your Explorer to a qualified mechanic. Attempting repairs without proper knowledge can lead to further damage or injury.
