Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1986 Mercury Grand Marquis LS, 4D SedanFACTORY OEM SERVICE PROCEDURE
TFI Ignition Module: 3.8L
- Disconnect "Spout" in-line connector at TFI module. Connect Spark Tester (D81P-6666-A) between ignition coil wire and ground. Crank engine.
- If spark is present at tester, perform STATOR test. If spark is not present, perform IGNITION COIL PRIMARY RESISTANCE test.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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