1. The Obvious:
* Bulbs: Start by checking all your turn signal bulbs (front and rear, both sides). A burned-out bulb is the most common cause of a blinking turn signal. Replace any that are faulty. Make sure you're using the correct wattage bulb specified in your owner's manual.
* Hazard Lights: Try your hazard lights. If they work normally, the problem is likely in the turn signal switch or wiring related to one specific side. If the hazards also blink rapidly, it points to a bulb issue (even a partially blown one).
2. More Advanced Troubleshooting:
* Turn Signal Switch: A faulty turn signal switch is another common culprit. This switch is usually located on the steering column. Sometimes, simply jiggling the steering wheel can temporarily restore function, suggesting a failing switch that needs replacing.
* Wiring: Inspect the wiring harness for any damaged, loose, or corroded wires, especially near the bulbs and the turn signal switch. Look for broken connectors. A visual inspection is usually insufficient; you may need a multimeter to test continuity.
* Turn Signal Relay: The relay is an electronic switch that controls the flow of electricity to the turn signals. A bad relay can cause intermittent or rapid blinking. The relay's location varies by vehicle; consult your owner's manual or an online repair manual (like those found on sites like Haynes or Chilton) to locate it. You can often test the relay by swapping it with a known good relay of the same type (often found in other parts of the vehicle's electrical system).
* Control Module: In some cases, the body control module (BCM) can be responsible. This is a more complex issue requiring a diagnostic scan tool to identify any related fault codes.
* Grounding Issues: Poor grounding can disrupt the electrical signal. Check the ground wires for corrosion or looseness.
3. Tools and Resources:
* Owner's Manual: This is your first resource; it contains bulb specifications and may have troubleshooting tips.
* Multimeter: Essential for testing voltage, continuity, and resistance in the wiring.
* Repair Manual: A Haynes or Chilton manual for your specific year and model Alero will provide detailed diagrams and repair procedures.
* Online Forums: Websites and forums dedicated to Oldsmobile Aleros may contain user-submitted solutions for similar issues.
Important Note: If you're not comfortable working on car electrical systems, it's best to take your Alero to a qualified mechanic. Incorrectly diagnosing and repairing electrical problems can lead to further damage. Always disconnect the negative battery terminal before working on the vehicle's electrical system.
