How to Change the Alternator in a 2004 Chevy Trailblazer

Chevrolet Trailblazer's 4.2-liter engine appeared on the Ward's 10 best engines list from 2002 through 2005 for its innovative double overhead cams (DOHC) and variable timing (VTT) on the exhaust. Replacing the alternator on a 2004 Chevy Trailblazer is not a difficult job and can be done with minimum tools. It is important to realize that the battery and alternator work in unison: If the battery has bad cells or becomes discharged, it can cause the alternator to overwork, which will raise its operating temperature to dangerously high levels. Always charge a dead or low battery before starting the engine, to reduce damage on the alternator.

Instructions

1

Disconnect the battery negative cable, using a wrench. Place the ratchet in the hole in the accessory belt tensioner and push the tensioner away from the belt. With the belt loose, take the belt off the alternator only -- there is no need to remove it from the other accessories.

2

Remove the two bolts securing the alternator to the mounting bracket, using a socket. Lift the alternator off the bracket and turn it face-down. Pull the plastic field wire plug out of the alternator. Remove the nut from the battery positive terminal (the terminal with the red wire), using a wrench.

3

Lay the new alternator face-down over the alternator-mounting bracket. Install the battery positive wire and tighten the nut. Plug the plastic field wire connector into the alternator.

4

Install the alternator into its mounting bracket, aligning the holes and inserting the two bolts. Tighten the bolts with a socket. Install the ratchet into the belt tensioner and push it away from the belt. Install the belt on the alternator pulley and release the tension on the belt. Install the negative cable on the battery and tighten it with a wrench.