Simply disconnecting the battery won't work reliably to reset it. While it might temporarily clear the light, the underlying problem will still be present, and the light will return.
Here's what you should do:
1. Get the diagnostic trouble code (DTC): You'll need an OBD I code reader. These are relatively inexpensive and can be found online or at auto parts stores. These older OBD I systems don't use the standardized OBD II connector, so make sure you get one that works with your car's system. The code reader will tell you *why* the light is on.
2. Address the problem: Once you have the code, you can look it up in a repair manual (Haynes or Chilton are good options) or online to identify the potential cause. This could be anything from a faulty oxygen sensor to a problem with the ignition system. *Fix the underlying issue.*
3. Clear the code: After fixing the problem, use the code reader to clear the DTC. The SES light should then turn off. If it doesn't, there might be a more serious issue that needs further investigation.
Important Considerations:
* Ignoring the light is risky: Driving with a malfunctioning system could cause further damage to your engine or even lead to a breakdown.
* Professional help: If you're not comfortable diagnosing and repairing the problem yourself, take your Grand Marquis to a qualified mechanic. They have the tools and expertise to diagnose and fix the issue properly.
Trying to reset the light without addressing the underlying problem is not a solution and could lead to more significant and costly repairs down the road. Finding the root cause and fixing it is crucial.
