- A code reader
- A jumper wire
- A pen and paper
- A flashlight
Step 2: Locate the diagnostic port.
- In a 1996 Mercury Marquis, the diagnostic port is located under the dash on the driver's side.
- It is a rectangular connector with a black cover.
Step 3: Connect the code reader to the diagnostic port.
- Plug the code reader into the diagnostic port.
- Turn the ignition key to the "ON" position, but do not start the engine.
Step 4: Read the trouble codes.
- The code reader will display any trouble codes that are stored in the car's computer.
- Write down the trouble codes on a piece of paper.
Step 5: Look up the trouble codes.
- You can look up the trouble codes online or in a repair manual.
- The trouble codes will tell you what problem is causing the check engine light to come on.
Step 6: Fix the problem.
- Once you know what the problem is, you can fix it.
- You may be able to fix it yourself, or you may need to take your car to a mechanic.
Step 7: Clear the trouble codes.
- Once you have fixed the problem, you need to clear the trouble codes from the car's computer.
- You can do this with a code reader or by disconnecting the battery for a few minutes.
