How to replace the alternator — Honda Accord 2020

Tools you'll need

• Ratchet
• 10 mm, 12 mm and 14 mm sockets
• Serpentine belt tool or long breaker bar
• Torque wrench
• Multimeter

Parts you'll need

• New or remanufactured alternator (Denso or OEM equivalent)
• Serpentine belt (replace it if it is cracked or glazed)

Steps

1. Disconnect the negative battery terminalPark on a flat surface, set the parking brake, and open the hood. Disconnect the negative battery terminal first and tuck the cable aside so it cannot touch the post.
   Tip: Always disconnect the negative terminal first. The alternator power cable stays live until you do.
2. Clear access and photograph the belt routingRemove the plastic engine cover and the air intake duct so you can reach the front of the engine. Take a photo of the serpentine belt routing before you touch it.
   Tip: A phone photo of the belt routing saves you guessing later.
3. Release the belt tension and slip the belt offPut a serpentine belt tool or a long breaker bar on the tensioner and turn it to slacken the belt. Slip the belt off the alternator pulley and let the tensioner back slowly.
4. Unplug the connector and remove the power cableUnplug the small electrical connector on the back of the alternator, then remove the nut holding the thick battery cable and move the cable aside.
5. Remove the mounting bolts and lift the alternator outRemove the two mounting bolts holding the alternator to the engine. Support the alternator with one hand as the last bolt comes out, then lift the unit straight up and out.
   Tip: The alternator is heavy for its size. Keep a hand under it so it does not drop onto the radiator.
6. Compare the new alternator and bolt it inSet the old and new alternators side by side and confirm the mounting holes, pulley, and plug match. Set the new unit in place and start both bolts by hand before tightening them.
7. Reconnect the wiring and refit the beltReconnect the battery cable and tighten its nut, then plug the electrical connector back in until it clicks. Route the serpentine belt over the alternator pulley following your photo, then release the tensioner and confirm the belt sits in every pulley groove.
8. Reconnect the battery and check the charging voltageRefit the air intake duct and engine cover. Reconnect the negative battery terminal, start the engine, and check the battery voltage with a multimeter. It should read about 13.8 to 14.4 volts, and the battery warning light should stay off.

Safety first

Disconnect the battery first. The thick power cable on the back of the alternator is live even with the engine off, so never let a wrench bridge it to the engine block. If you are not confident, have a qualified technician do this job.