Squealing noises under the hood. Headlight bulbs that frequently burn out or appear dim. The dash voltmeter gauge, which monitors battery voltage, is showing readings that are too high or too low.
These are common indicators that the charging system may be malfunctioning.
If you notice these symptoms, follow these five steps to find the cause:
1.
Inspect under the hood. Check belt tension and condition. Examine electrical connections and cables for corrosion and tightness. Finally, make sure the alternator is mounted properly.
2.
Examine batteries for damage, cracked casing, loose terminals or leaks. Clean or repair connections and replace damaged batteries. Ensure batteries are matched in manufacturer, CCA rating and age. Test batteries using a standard battery test. Use a fully charged battery for accurate results.
3.
Check system voltage with the engine running. If 13.8 volts or higher, proceed to Step 4. If under 13.8 volts, measure voltage at alternator B+ and the alternator case (use a ground stud if insulated). Replace the alternator if the voltage is between 12.6 and 13.7 volts. If the voltage is 13.8 volts or higher, perform a voltage drop test. (See our
YouTube video for instructions.)
4.
Test the alternator output with an automated or manual method. Replace the alternator if it fails this test.
5.
Consult the service manual if you have completed the first four steps and the alternator works correctly. The issue is likely outside the alternator.
Extra Help: Battery & Alternator Testing Guides
Visit our
Technical Support page to download additional troubleshooting resources.
Pro Tip: Complete Every Step
If you find something wrong at any step, it’s wise to complete the remaining steps anyway to ensure you’ve given the charging system a thorough review.
Watch: Step-by-Step Alternator Diagnostics
Watch our
Tech Tip video to see these five steps in action.