Is it the alternator if the car wont turn over and you only hear a clicking noise when you turn the key to start a Ford Taurus - Mercury Sable?

Answer 1

Battery, or starter is bad. Now the battery could be dead due to a defective alternator. Clean the battery terminals, and charge the battery fully. Attempt to start the car. If if will not start, suspect a bad starter or starter solenoid. If it starts, check the voltage at the battery. Should be 13.5 to 15 volts. If less than 13 volts, suspect a defective alternator. Drive it to most auto parts stores and have the charging system load tested to be sure.

To check the alternator:I agree with the previous answer...however I would like to assist you in checking your alternator... While your car is running (after you fix the battery or starter obviously) pull the positive wire to the battery completely off...if the car stays running, your alternator is fine...However if the car dies, your alternator is faulty... Real simple...

More Information:

The clicking noise you can hear is the starter solenoid trying to engage this would mean your starter solenoid has packed up change the starter motor and it should be fine you may need to charge your battery depending on how long it has been sitting or how many times you have tried to start your car.

You may have a loose or corroded ground connection. Not just the battery ground but the engine to chassis ground. You may also have a bad battery cable. If you see swelling on any part of the cable, replace it. Make sure the connections are clean and tight. Did you replace the starter solenoid with the starter, or is it a separate item? If the solenoid is separate from the starter, it is probably bad. It is unlikely that the ignition switch is bad, but possible.