Symptoms:
* Battery light illuminates: This is the most common and obvious sign. The light will usually come on while the engine is running. Ignore it at your peril!
* Dim headlights: As the alternator fails, it can't keep up with the electrical demand, leading to dimming headlights, especially when the engine is idling or under load (e.g., using the AC, wipers, or radio).
* Other electrical issues: Other electrical components might malfunction or behave erratically. This includes things like the radio, power windows, and interior lights. They may flicker or stop working altogether.
* Engine stalling: In severe cases, a failing alternator might not provide enough power to keep the engine running, causing it to stall, particularly when under load.
* Clicking sound when starting: A weak battery, often a result of a bad alternator, can lead to a clicking sound when you try to start the car.
* Low voltage reading: You can use a multimeter to check the voltage at the battery terminals. With the engine *off*, it should read around 12.6 volts. With the engine *running*, it should be around 13.5-14.5 volts. A significantly lower reading while running indicates a problem with the alternator.
Testing the Alternator (requires a multimeter):
1. Voltage Test (Engine Running): This is the most basic test. Connect the multimeter to the battery terminals with the engine running. As mentioned above, you should see 13.5-14.5 volts. Lower than that suggests a problem.
2. Voltage Drop Test (Engine Running): This test is more precise and involves checking voltage at the alternator itself. This requires a bit more knowledge of automotive electrical systems, including knowing where the alternator's connections are located, and some might require removing the alternator's connectors. Consult a repair manual for your specific vehicle. A significant voltage drop across the wires indicates a problem.
3. Load Test: This involves placing a load on the electrical system (like turning on the headlights, AC, and wipers) while measuring voltage. If the voltage drops significantly under load, the alternator is likely failing.
Important Considerations:
* Battery Condition: A weak or failing battery can mimic the symptoms of a bad alternator. Have your battery tested to rule it out.
* Professional Diagnosis: If you're not comfortable performing electrical tests, it's best to take your Malibu to a qualified mechanic for diagnosis and repair. They have the tools and expertise to accurately assess the problem.
A bad alternator is a serious issue that can leave you stranded. Don't ignore the warning signs! Address the problem promptly to avoid further damage to your battery and other electrical components.
