* Bad starter motor. The starter motor is responsible for turning the engine over. If it's bad, it won't be able to do its job, and you'll hear a clicking noise instead.
* Bad solenoid. The solenoid is a switch that connects the battery to the starter motor. If it's bad, it won't be able to complete the circuit, and you'll hear a clicking noise instead.
* Loose or corroded battery terminals. If the battery terminals are loose or corroded, they won't be able to make a good connection with the battery, and you'll hear a clicking noise instead.
* Bad ignition switch. The ignition switch is responsible for turning on the power to the starter motor. If it's bad, it won't be able to do its job, and you'll hear a clicking noise instead.
To troubleshoot the problem, you'll need to check each of these components. You can start by checking the battery terminals. If they're loose or corroded, tighten them or clean them off. If that doesn't fix the problem, you'll need to check the starter motor, solenoid, and ignition switch.
If you're not comfortable doing this yourself, you can take your Ford Explorer to a mechanic for diagnosis and repair.
