Possible Causes:
* Low Battery Voltage: This is the most common cause. A weak battery can cause erratic electrical behavior, including flashing lights. Check the battery terminals for corrosion and have the battery tested at an auto parts store. A simple voltage test with a multimeter will confirm if it's holding a charge.
* Alternator Problems: If the alternator isn't charging the battery properly, the lights will flash, especially when the engine is running. Have the alternator tested as well.
* Body Control Module (BCM) Issues: The BCM controls many electrical functions in the car. A malfunctioning BCM can cause various electrical problems, including intermittent flashing lights. This is a more complex issue requiring professional diagnosis.
* Faulty Wiring: A short circuit or damaged wiring somewhere in the system could be responsible. This is difficult to pinpoint without professional tools and expertise.
* Interior Light Switch: Though less likely, a problem with the interior light switch itself (possibly a short) could cause the lights to flash intermittently.
* Loose Ground Connection: A poor ground connection can disrupt the electrical system and cause strange behavior like flashing lights.
Troubleshooting Steps:
1. Check the Battery and Alternator: This should be your first step. Have both tested at an auto parts store. This is the cheapest and easiest fix if the problem lies here.
2. Inspect the Wiring: Visually inspect the wiring harness for any obvious damage, cuts, or loose connections, especially around the interior light fixtures and the BCM. This is more difficult and may require some disassembly.
3. Test the Interior Light Switch: If you're comfortable doing so, you can try disconnecting the interior light switch and see if the flashing stops. If it does, the switch is likely faulty.
4. Check for Loose Ground Connections: Look for any ground wires that might be loose or corroded. These are often found near the battery and chassis. Clean and tighten them if necessary.
5. Have it Diagnosed Professionally: If you've checked the battery, alternator, and wiring and still have flashing lights, it's best to take your Concorde to a qualified mechanic or auto electrician. They have the tools to diagnose more complex electrical problems, such as issues with the BCM. They can also check for any stored diagnostic trouble codes (DTCs) that might indicate the root cause.
Important Note: Driving with a faulty electrical system can be dangerous. If you suspect a serious problem, it's best not to drive the vehicle until it's been repaired.
