How to Replace an Alternator

Below guide will teach you How to Replace an Alternator . Please follow the instructions carefully.

Things You’ll Need:

  • Screwdriver
  • Combination Wrench Set
  • Socket and Ratchet Set
  • Serpentine Belt Tool
  • Alternator

Estimated Costs:

  • DIY Costs: Est. $35.87 parts only
  • Shop Costs: Est. $170.33 parts and labor


  • Prop the engine hood up. Look for the alternator. You may have to consult the owner’s manual to locate the position of the alternator.
  • Test the battery voltage with the help of DMM or digital multimeter. If the battery is bad or dead it will show you nothing more than 9 volts which is not enough to initiate the ignition process for most of the vehicles.
  • In order to determine whether the alternator is defective or not, you need to have a battery fully charged and need to clear the load test.
  • When you are sure that the battery is fully charged, plug the DMM to the battery terminals. It will show you reading between 12-13 volts. Make sure that the engine is off.
  • Now turn the engine on and again check the reading on DMM. It will show the reading between 13.5-14.5 volts.
  • Discard the negative battery cable from terminal.
  • Next, discard the wiring connections (power and ground) on the alternator. Mark the position of each wire so that you can connect them accurately.
  • Unfasten the alternator bracket bolts along with alternator adjusting bolts. This will help you getting rid of the alternator drive belt.
  • Unfasten the alternator mounting bolts along with spacer, adjusting bolt and lower pivot bolt with ratchet or socket wrench. Take the alternator out.
  • Now place the new alternator in its respective place and hand tighten the mounting bolts, spacer, adjusting bolt and lower pivot bolt.
  • Slide the alternator belt onto the alternator and adjust it properly.
  • When the alternator belt is tight enough, fasten the mounting bolts.
  • Reconnect the power and ground wires along with other wiring connectors.
  • Check the tension in the belt by pressing the belt down in the middle. If it is loose, adjust the alternator belt tension.
  • Reattach the negative battery cable back onto the negative terminal.
  • Switch the vehicle on and retest the battery voltage with the help of DMM.
  • After verification of voltage, switch the engine off and check the alternator belt tension again.

Further Reading

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