How to Change an Alternator

When a vehicle's alternator is functioning properly, it will put out between 13 and 18 AC volts that power the electronics and ignition system while recharging the battery. But, if it delivers less than 13 volts, the alternator will fail to keep the battery recharged. You can save money when you replace your alternator by doing it yourself and following the steps below.

Steps

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    Disconnect the positive battery cable. Please take note the positive battery cable is red an not black.
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    Locate the alternator on your particular vehicle.
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    Use a serpentine belt tool to loosen the belt and move it off the pulley of the alternator.
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    Put back the bolts that hold the alternator in place. It will be a minimum of 2, and no more than 4, bolts depending on your make and model.
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    Employ a socket and ratchet to loosen and remove the bolts.
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    Pull out the alternator, then unplug and remove the nut for any electrical connections.
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    Remove the alternator from the engine and take it to the parts house in order to get a new or rebuilt one.
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    Inspect the new alternator, while still at the parts house, comparing it to the old one. Make sure the voltage regulator and pulley match up to the old one. If it does not, get the parts house to put the old pulley assembly on the new one.
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    Reverse the process to install the new alternator.
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    Connect the electrical plugs and wires onto the new alternator.
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    Slide the alternator into place and begin threading the old bolts in the right position.
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    Put the alternator pulley back into place, bolting it down. Be sure to check the alignment with the belt tensioner pulley.
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    Use the serpentine belt tool to get the slack you need and slip the belt back over the alternator pulley. Now release the tool by putting tension on the belt.
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    Reconnect the positive battery cable.
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    Start up your car and make sure the alternator is charging.

Tips

  • Take photos with your digital camera as you remove parts. This shows what came from where. It will also make it easier to remember the sequence when you put it back together.
  • Many auto parts houses will loan you the serpentine belt tool for a small refundable deposit.
  • If you have trouble finding the serpentine belt tensioner, use the drawing of the belt that is most likely located in the engine bay compartment.
  • When you return the serpentine belt tool, ask the parts house if it will check the voltage your new alternator is putting out. Most parts houses will do this for free. The voltage should be at least 13 volts.

Warnings

  • Disconnect the positive battery cable before you work on any electrical parts in your vehicle to prevent shorting out the electrical system and damaging the electronics.
  • Always allow the engine to cool down before you begin working near it to prevent burning yourself.
  • When putting the old bolts back onto the new alternator, do not tighten them down until all have been added.

Things You'll Need

  • Alternator
  • Serpentine belt tool
  • Sockets and a ratchet SAE or Metric
  • Wrenches SAE or Metric

Article Info

Categories: Cars & Other Vehicles