Possible Causes:
* Faulty PATS Module: This is the most likely culprit. The module itself might be malfunctioning, preventing communication with the key.
* Bad Ignition Switch: The switch might be failing, preventing proper communication with the PATS module.
* Low Battery Voltage: A weak battery can sometimes cause intermittent PATS issues.
* Key Fob Issues: While less likely with a blinking light, a problem with the key fob's battery or internal transponder could contribute. Try another key if you have one.
* Wiring Problems: Damaged or corroded wiring between the PATS module, ignition switch, and other components can interrupt the signal.
* Immobilizer System Malfunction: This is related to the PATS system; a broader component failure within the anti-theft system.
Troubleshooting Steps:
1. Check the Battery: Start with the simplest check. Test the battery voltage with a multimeter. A low voltage can cause erratic behavior. Charge or replace the battery if necessary.
2. Try a Second Key: If you have a spare key, try starting the car with it. If the spare key works, your primary key fob is likely the problem (battery or internal transponder).
3. Inspect the Ignition Switch: Look for any signs of damage or corrosion around the ignition switch. This is often a difficult repair, potentially requiring professional help.
4. Have the PATS System Scanned: A professional mechanic with diagnostic equipment can scan the vehicle's computer system for diagnostic trouble codes (DTCs). This will pinpoint the exact problem within the PATS system. Many auto parts stores offer free code scanning.
5. Consider the PATS Module: If the scan reveals issues with the PATS module, it likely needs to be replaced or reprogrammed. This is a more advanced repair and usually requires a specialized tool. You'll likely need a professional mechanic for this.
6. Wiring Inspection (Advanced): This requires experience with automotive electrical systems. Checking for broken or corroded wires related to the PATS system is a difficult task without a wiring diagram and expertise.
Important Considerations:
* Professional Help: Given the complexity of the PATS system, seeking professional help from a qualified mechanic is often the best approach, especially if you are not comfortable working on car electronics.
* Cost: Replacing the PATS module or ignition switch can be expensive, depending on labor costs and parts.
* Security Concerns: A malfunctioning PATS system can leave your vehicle vulnerable to theft. Don't delay seeking repairs.
In short, a blinking theft light and stalling engine on a 2002 Ford Taurus strongly suggests a problem with the PATS system. Getting a diagnostic scan is the crucial first step to determine the specific cause and get your vehicle repaired safely and securely.
