Toyota Highlander uses the serpentine belt, also called the multi-accessory drive belt, to control all engine accessories, i.e., the power steering, air conditioner compressor, water pump and alternator. Located at the front of the crankshaft, the serpentine belt winds around the pulleys connected to the various accessories and ultimately around a tension pulley that keeps the belt at the correct contact tension so that all the engine accessories engage properly. Changing the serpentine belt on a Toyota Highlander is a fairly simple do-it-yourself project that requires the proper sized wrench or socket set. Toyota recommends examining the serpentine belt on the Highlander for fraying, cracking and/or missing chunks, twice per year or every 25,000 miles.
Check to ensure the Toyota Highlander's engine is cold, then make sure the Highlander is in park, the ignition is in the off position and the key is removed from the ignition to prevent any possibility of the engine engaging during the serpentine belt replacement.
Open the bonnet and locate the serpentine belt routing diagram sticker on the side of the engine casing, which is present to ensure the proper installation of the new belt. Study it for a moment before removing the existing belt as it is essential the new belt be installed exactly as the diagram indicates.
Find the tensioner pulley, the main pully that controls the Highlander's serpentine belt, and fit a 1/2-inch socket wrench over the self-tensioner on the outside of the pulley.
Pull the wrench to the left to move the pulley forward, which loosens the belt, then remove the belt.
Compare the old serpentine belt with the new, replacement belt for length, width and number of grooves on the belt's underside to be certain the replacement belt is the right part for the Highlander.
Fit the new belt onto each pulley according to the serpentine belt routing diagram on the Highlander's manufacturer sticker. Fit the new belt onto the tensioner pulley last, again applying pressure on the pulley's self-tensioner with the 1/2-inch socket wrench to loosen the pulley.
Release the pressure on the self-tensioner and allow the tensioner pulley to ease back into place, thereby tightening the new serpentine belt with the appropriate tension.
Remove the wrench and close the bonnet.
If the serpentine belt routing diagram on the Sienna is torn or blackened, or is for any reason unreadable, draw a rough picture of exactly how the existing belt is routed through the various engine accessory pulleys prior to removing it.