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.
1990 Mercury Grand Marquis LSFACTORY OEM SERVICE PROCEDURE
Starter Load Test
- Connect starting system test equipment. See Fig 1 . Ensure no current is flowing through ammeter and carbon pile rheostat of starter load tester. Disconnect terminal "S" push-on connector from starter relay.
- Ensure transmission is not in gear. Connect remote control starter switch between terminal "S" and positive battery terminal. Crank engine and observe voltmeter reading. Stop cranking engine and adjust carbon pile rheostat until voltmeter indicates same reading as obtained while cranking engine.
- Ammeter will indicate starter current draw under load. Normal starter current load is 150-210 amps on permanent magnetic system and 150-250 amps on positive engagement system.
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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