Extreme weather conditions can take a toll on your car battery. Proper battery maintenance can help keep your car starting, but what do you do when your Mercury Marquis won't crank or turn over? Look at the electrical system when troubleshooting an engine that will not start. The engine will not turn over because the starter is not receiving the proper voltage. Troubleshooting your Mercury Marquis can be accomplished with a few basic tools, and an hour of your time.
- Skill level:
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Things you need
- Digital voltmeter
- Small wire brush or old tooth brush
- A roll of black electrical tape
- Safety glasses
- Rubber gloves
- Steel wool or scouring pads
Open the fuse box. The Mercury Marquis fuse box is located under the dash on the driver's side console. Inspect all the fuses. Replace any fuses that are blown or damaged. Open the bonnet, and set the prop rod to hold the hood open. Inspect the harness and electrical connections. Verify that they are secure, and free of damage, abrasion and corrosion. If abrasion is found and the wire is exposed, temporarily wrap the wire with electrical tape. Repair or replace the wire as soon as possible.
Inspect the battery. The recommended battery for the Mercury Marquis is 12 volts with 650 CCA or cold cranking amps. Remove all corrosion, dirt, oil and debris. Use baking soda and a small brush to remove any corrosion. Disconnect the negative battery cable, then disconnect the positive battery cable. Sprinkle baking soda on the corroded area. Dip the brush in a cup of water, and scrub the terminal to remove the corrosion. Continue on the other effected areas. When complete, connect the positive battery connection, then correct the negative battery connection. Be sure the battery terminals connections are tight.
Inspect the chassis ground frame connection or your Mercury Marquis. The connection should be free of corrosion, rust, paint, oil, dirt and debris. Use steel wool or a scouring pad to remove rust and paint from the frame connection. If needed, reconnect the chassis ground frame connection.
Set a digital voltmeter to measure resistance. Place the positive probe on the minus battery terminal, and place the negative probe on chassis ground. The resistance should be less than one ohm. If the resistance is greater than one ohm, replace the cable.
Set a digital voltmeter to measure voltage. Place the positive probe on the positive battery terminal, and place the negative battery probe on the negative battery terminal. The voltage should be approximately 12.6 volts. If the voltage is less than 10 volts, charge the car battery using a charger.
Measure the voltage across the starter solenoid. Place the positive probe on the positive terminal, and place the negative probe on chassis ground. Have someone turn the Mercury Marquis key switch to "START" while you monitor the voltage. The voltage should be approximately 12.6 volts. If the voltage is correct, verify that the connections to the starter are secure and free of corrosion, oil, dirt and debris. If the connections are clean, remove the starter and retest. If the voltage is not correct, the problem may lie within the starter relay.
Follow the wires from the starter solenoid to the starter relay. Verify that the wires are free of damage, corrosion, oil, dirt and debris. Repair as required. Use the digital voltmeter to measure the voltage across the starter relay coils. Place the positive probe on terminal 85, and place the negative probe on terminal 86. Have someone turn the Mercury Marquis key switch to "START" while you monitor the voltage. The voltage should be approximately 12.6 volts. If the voltage is correct, replace the starter relay. If the voltage is not correct, there is a problem in the wiring from the start switch to the fuse/relay box. Repair any loose or damaged connections.
Tips and warnings
- Many auto parts stores will test your battery, alternator and starter for you.
- Always wear safety glasses when working around the vehicle battery.
- Wear rubber gloves when cleaning the battery.
- When disconnecting the battery, disconnect the negative battery connection before removing the positive battery connection.
- When reconnecting the battery, connect the positive battery connection before connecting the negative battery connection.
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