How to Troubleshoot the Charging System on a 1998 Ford Windstar

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    • 1). Open the hood and feel the tension on the accessory belt. It should have good tension and the tensioner should move freely. If there is little tension replace the belt tensioner (a common problem).

    • 2). Place the red voltmeter lead on the battery positive terminal and the black lead on the negative terminal. The voltmeter should display 12.3 to 12.7 volts if the battery is fully charged. If it shows less than desired, the question is whether it is a battery or alternator problem.

    • 3). Charge the battery and retest it for voltage. If it still has less than desired, replace the battery. Proceed with a good battery -- either new or charged.

    • 4). Remove the voltmeter and connect the load tester with the red terminal on the battery positive and the black on negative. This test is not necessary on a new battery, only on a recently charged battery. Press the load button for 10 seconds and release. Check the voltage on the tester. The voltage should not drop below 10.5 volts or the battery has a bad cell -- replace it.

    • 5). Remove the load tester and attach the voltmeter to the battery again. Start the engine and observe the alternator voltage. The displayed voltage should be 13.8 to 14.5 volts. Lower voltage indicates a bad diode trio in the alternator, which will require replacing the alternator. If the voltage is within the proper range, turn on the air conditioning and the lights. The voltage should drop momentarily and as fast as it drops, it should rise back to the same range. If the voltage drops past 13.7 volts and never recovers, the voltage regulator, which is also inside the alternator, is bad. Replace the alternator. In order to charge the battery, the alternator must put out at least 13.8 volts when a load is placed on it. Anything less and the battery would forever be losing ground in its effort to charge.


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