How to Change Out a Toyota Sienna Alternator

The alternator in your vehicle is a critical component responsible for the charging of the battery as well as providing electricity to the ignition system. Changing it can be tough on some vehicles, but overall it is a job that most home mechanics can handle. The Toyota Sienna has an alternator mounted on the drivers side of the engine and requires just two bolts and two wire connections be disconnected for removal of the alternator.

Things You'll Need:

• Metric socket set
• Metric open end wrenches
• Torque wrench

1. Disconnect the battery terminals

Disconnect the battery terminals from the battery and lay them off to one side. You will be working with electrical connections at the alternator, so this is a step that must be completed for safety reasons.

2. Locate the alternator on the driver's side

Locate the alternator on the driver's side, in front of the engine. You will see two bolts holding the alternator in place. Locate the adjustment bolts on the right side of the alternator.

3. Loosen the adjustment bolt

Loosen the adjustment bolt, as well as the mounting bolt on the left side of the alternator and remove the belt from the pulley. Make note of the path the bolt follows over the pulleys before removing it to allow for easier replacement of the belt.

4. Remove the two electrical connectors

Remove the two electrical connectors on the alternator. The first is a pinch type connector on the rear of the alternator and the second will be bolted to the top of the alternator. Set these both aside and remove both the adjustment bolt and the mounting bolt and lift the alternator out of the engine compartment.

5. Place the new alternator into the engine compartment

Place the new alternator into the engine compartment and align the mounting holes with the threaded holes in the mounting bracket. Insert the mounting bolt first but do not tighten it yet.

6. Insert the adjustment bolt into the alternator

Insert the adjustment bolt into the alternator and bracket leaving it loose enough to move the alternator body around on the bracket. Reinstall the pinch connector on the rear of the alternator, then attach the larger cable on top of the alternator using the nut and washer included.

7. Replace the belt on the pulleys

Replace the belt on the pulleys making sure that it follows the original path over all pulleys on the engine and adjust it by pulling the alternator away from the engine until the the tension on the belt is snug. Tighten the adjuster bolt until it is snug.

8. Tighten the mounting bolt

Tighten the mounting bolt until it is snug and check the belt tension. The belt needs to be tight enough to not slip but should still have a slight amount of deflection in it when you apply pressure to it between the pulleys.

9. Tighten both bolts

Tighten both bolts and torque them to the manufactures specifications. Reinstall the battery cables on the terminals and test run the engine.

Tips and Warnings

Using a torque wrench on the bolts of the alternator will keep you from stripping the threads in the mounting bracket.

Never over tighten the belt on the engine. It will result in premature wear or failure of the belt.

Video showing how to replace a Toyota alternator:

Comments from the video:

• Incredible! I just spent a few hours following your step-by-step tutorial and replaced our alternator. Thank you so much!
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