How to Change the Alternator: 15 Steps (with Pictures)

2025 Author: Samantha Chapman | [email protected]. Last modified: 2025-01-24 13:28

When working properly, a car's alternator provides between 13 and 18 volts to power the electronic and starter systems while the battery recharges. However, if it supplies less than 13 volts, the alternator cannot keep the battery charged. You can save on replacing the alternator by doing it yourself. Follow these instructions.

Steps

Step 1. Disconnect the positive pole lead from the battery

Step 2. Locate the alternator on the vehicle you are repairing

Step 3. Use a serpentine tool to loosen the belt and remove it from the alternator pulley

Step 4. Remove the nuts holding the alternator in place

There should be at least 2, but no more than 4, depending on the car model.

Step 5. Use a screwdriver and ratchet to loosen and remove the bolts

Step 6. Remove the alternator and then disconnect and remove the nut from each electrical connection

Step 7. Remove the alternator from the engine compartment and take it to the parts store to buy a new or rebuilt one

Step 8. Check the new alternator while you are still in the parts shop and compare it with the old one

Make sure the voltage regulator and pulley match the ones you removed. If not, ask the shop to fit the old pulley to your new alternator.

Step 9. Follow the reverse procedure and install the new alternator

Step 10. Restore the electrical connections and cables to the new alternator

Step 11. Put the alternator in its place and start fixing the bolts in the right position

Step 12. Put the pulley back in place and secure it with the bolts

Be sure to check the alignment with the belt pretensioner.

Step 13. Use the serpentine tool to have the clearance you need to slide the belt over the alternator pulley

Now release the tool and tension the belt.

Step 14. Reconnect the positive cable to the battery

Step 15. Start the car and make sure the alternator is charging

Advice

Take pictures with a digital video camera when you take apart the various parts. So you will remember the exact position and know how to reassemble them.
When you return your coil tool, ask the parts shop if they can check the voltage of your new alternator. Most stores do this for free. The voltage should be at least 13 volts.
Many parts stores rent you a serpentine tool for a small fee and with a refundable security deposit.
If you can't find the serpentine belt use the connecting belt, which is probably located in the engine compartment.

Warnings

Always wait for the engine to cool down before starting work to avoid getting burned.
Disconnect the positive battery cable before working, to avoid short circuits in the electrical system and damage to electronic instruments.
When putting the old nuts back on the new alternator, do not fully tighten them until you have put them all back.

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