ALTERNATOR TEST 3

And now for the last test. As mentioned in the last section, the alternator needs a power source to start charging the battery. On the older Ford 3.0L and 3.8L Vehicles, this power source is provided by the alternator itself once it's pulley starts spinning. On the newer Ford vehicles, this power is provided by a fuse in the Engine Compartment Fuse Box.

To find if your vehicle does have this fuse or not, you'll need to consult your vehicle's owner's manual.

If your vehicle does not have this fuse, you can disregard this test and replace the alternator. If your vehicle does have this fuse, then proceed with the test:

  1. 1

    Reconnect the battery to its battery negative (-) cable, that you disconnected in the previous test.

  2. 2

    Locate the alternator fuse, which will be located in the fuse box in the engine compartment.

  3. 3

    Once you have located the fuse, remove it and check that it's not blown.

  4. 4

    If it is blown, replace it with a new one and repeat ALTERNATOR TEST 1.

Let's take a look at what your test results mean:

CASE 1: The fuse is NOT blown. This is good and confirms that the alternator is getting the voltage it needs to begin charging.

Now, since it is not charging, and taking into account all of your test results so far, you can conclude that the alternator is bad and needs to be replaced. Replace the alternator.

CASE 2: The fuse IS blown. This tells you that the voltage regulator is not getting power.

Replace the fuse and start the vehicle up and check to see if the alternator is charging the battery.

Symptoms Of A Bad Alternator

The most common symptom of a bad alternator are:

  1. 1

    The battery light will be illuminated on your Ford vehicle's instrument cluster to let you know that yes, there's something wrong.

  2. 2

    The headlights glow dim when turned on at night.

  3. 3

    A jump start easily starts your car (or pick up or mini-van) but after a few minutes, it dies.

  4. 4

    Every time you re-charge the battery, the vehicle starts fine, but after the initial trip, it needs to be jump-started.

Related Test Articles

There are more 3.0L and 3.8L V6 articles that I've written to help you troubleshoot your 3.0L or 3.8L v6 equipped vehicle that you can check out. For the articles in this Web Site, go the Ford 3.0L, 3.8L Index Of Articles.

Here's a sample of the articles you'll find in the index:

  1. How To Test A Bad Starter Motor (Ford 3.0L, 3.8L).
  2. How To Test The Fuel Injectors (Ford 3.0L, 3.8L).
  3. How To Do And Interpret An Engine Compression Test (Ford 3.0L, 3.8L).
  4. How To Test The Ford V6 Ignition Coil Pack (at: easyautodiagnostics.com).
  5. How To Test The Ignition Control Module (Older 3.0L And 3.8L With A Distributor) (at: easyautodiagnostics.com).
  6. How To Test The MAF Sensor (at: easyautodiagnostics.com).
  7. How To Test The Throttle Position Sensor (TPS) (at: easyautodiagnostics.com).
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Ford Vehicles:

  • Aerostar 3.0L
    • 1992, 1993, 1994, 1995, 1996, 1997
  • Mustang 3.8L
    • 1997, 1998, 1999, 2000, 2001, 2004
  • Probe 3.0L
    • 1990, 1991, 1992
  • Ranger 3.0L
    • 1991, 1992, 1993, 1994, 1995, 1996, 1997

Ford Vehicles:

  • Taurus 3.0L, 3.8L
    • 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Tempo 3.0L
    • 1992, 1993, 1994
  • Thunderbird 3.8L
    • 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997

Lincoln Vehicles:

  • Windstar 3.0L, 3.8L
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003

Lincoln Vehicles:

  • Continental 3.8L
    • 1989, 1990, 1991, 1992, 1993, 1994

Mercury Vehicles:

  • Cougar 3.8L
    • 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
  • Sable 3.0L, 3.8L
    • 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Topaz 3.0L
    • 1992, 1993, 1994

Mazda Vehicles:

  • B3000 3.0L
    • 1994, 1995, 1996, 1997