Troubleshooting Steps:
1. Check the battery cables: Inspect the positive (+) and negative (-) cables connecting the battery to the alternator and the battery to the chassis. Look for corrosion, loose connections, or broken wires. Clean the terminals thoroughly if needed.
2. Check the alternator's connection to the battery: This is sometimes overlooked. Ensure the positive cable from the alternator is securely connected to the battery's positive terminal (or a terminal it connects to).
3. Check the alternator's output: Even if your alternator tests good, a faulty internal regulator can still prevent proper charging. Use a voltmeter to check the voltage at the alternator's output terminals while the engine is running. You should see around 13.5-14.5 volts. If it's significantly lower, the alternator itself might be the problem (even with a prior good test).
4. Check the charging system fuses and relays: Your Ford Ranger has several fuses and possibly a relay related to the charging system. These are usually located in the underhood fuse box and the passenger compartment fuse box. Consult your owner's manual to identify the correct fuses and relays. Look for blown fuses (broken filaments) and replace them as needed.
5. Check the wiring: Look for any damaged or broken wires in the charging circuit. This is often difficult but worth checking, especially around the alternator and battery connections.
6. Check the ignition switch: A faulty ignition switch can interrupt power to the alternator. This is less common, but worth considering if all other checks fail.
Where to find fuse boxes: Your owner's manual will be your best guide for the exact locations of the fuse boxes (under the hood and inside the passenger compartment) and what each fuse controls.
Important Note: If you're not comfortable working with car electrical systems, it's best to take your Ford Ranger to a qualified mechanic. Incorrectly working with car electrical systems can be dangerous.
