* Weak Battery: Even if the charger showed a full charge, the battery might have a bad cell or internal damage that prevents it from delivering the high current surge needed to crank the engine. This is the most likely culprit given your description.
* Bad Battery Cables: Corroded, loose, or damaged battery cables can prevent sufficient current from reaching the starter motor. Check for corrosion at both battery terminals and the connections to the starter.
* Faulty Starter Motor: The starter itself could be failing. The single click is a common symptom of a weak or failing starter solenoid (part of the starter).
* Bad Starter Solenoid: As mentioned above, this is a component of the starter motor and is a common point of failure.
* Faulty Ignition Switch: Though less likely, a problem with the ignition switch could prevent power from reaching the starter.
Here's how to troubleshoot:
1. Check the Battery Terminals and Cables: Inspect the battery terminals for corrosion. Clean them thoroughly with a wire brush and baking soda and water solution. Also, check the cables for any damage or looseness. Tighten connections securely.
2. Jump Start the Truck: Try jump-starting the truck from another vehicle. If it starts easily, the problem is likely with your battery or charging system. If it doesn't jump start easily, the problem is more likely the starter motor, cables or possibly the ignition switch.
3. Test the Battery: If possible, have the battery tested at an auto parts store. They can check its voltage, cranking amps, and overall health. A load test is particularly important to determine if it can deliver the high current needed to start the engine.
4. Check the Starter: If the battery tests good and the cables are fine, the starter motor is the prime suspect. This often requires a mechanic to diagnose and replace.
In short: The single click points to insufficient power reaching the starter. Start by checking the battery and cables, and if those are okay, then suspect the starter motor or solenoid. You likely need professional help to replace either of those if they are faulty.
