The Most Likely Culprits:
* Low Battery Voltage/Alternator Issues: This is the most common cause. The turn signals draw a small amount of power, but if your battery is weak or your alternator isn't charging properly, the added load can cause the car's computer to shut down to prevent a complete electrical failure. A dying battery will often exhibit other symptoms like slow cranking or dimming headlights.
* Faulty Voltage Regulator: The voltage regulator controls the output of the alternator. A malfunctioning regulator can cause erratic voltage fluctuations, leading to the car shutting off when an additional electrical load (like the turn signals) is applied.
* Wiring Issues: A short circuit or a loose connection in the wiring harness related to the turn signals or the car's electrical system could cause a sudden power loss when the signals are activated. Corrosion is a common culprit in older vehicles.
* Failing Ground Connection: A poor ground connection can disrupt the flow of electricity. This can lead to inconsistent voltage, causing various electrical components to malfunction, including the car shutting off under load.
* Faulty Body Control Module (BCM) or other Control Modules: These modules control various aspects of the vehicle's electrical systems. A malfunctioning BCM, particularly if it's responsible for power distribution, could cause the car to shut down when a specific circuit (like the turn signals) is activated. This is less likely but possible.
Less Likely, but Possible:
* Ignition Switch Problem: Though rare, a failing ignition switch could contribute to the issue. This would likely manifest in other ways as well (e.g., intermittent starting).
What to Do:
1. Check the Battery: Have the battery tested at an auto parts store. They can check voltage and the charging system. This is the first and most important step.
2. Inspect Wiring (If you are comfortable with car repair): Carefully inspect the wiring harness related to the turn signals for any obvious damage, loose connections, or corrosion.
3. Professional Diagnosis: The most reliable way to pinpoint the problem is to take your car to a qualified mechanic or auto electrician. They have the tools and expertise to diagnose electrical issues accurately, which can be complex.
Driving with this problem is dangerous. Your car could shut off unexpectedly, leading to an accident. Avoid driving the vehicle until the problem is diagnosed and fixed.
