If the alternator on your 1999 Chevy Lumina is not keeping your battery charged or has started to make noise when the car is running, it is time to test and replace it. Metallic scraping or grinding noises coming from the alternator indicate a bad bearing assembly inside the case. A consistently low battery may indicate the alternator or voltage regulator is failing. In either case, replacement of the alternator is the best option. Replacement alternators are available at most auto parts store and if you bring in your old one, they will often bench test it free.
Remove the negative battery cable from the battery. Loosen the retaining bolt and lift the cable off the battery terminal. Isolate the cable from the battery while you are working.
Locate the serpentine belt tensioner on the front of the engine. Use a socket and ratchet to rotate the tensioner counterclockwise to loosen it then remove the belt from the alternator pulley.
Locate the wiring harness connections on the back of the alternator. There are two, a plug-in connector and a stud with a retaining nut. Depress the locking tab on the plug-in connector and pull it out of the alternator.
Remove the nut on the “B” terminal, the stud on the back of the alternator, with a wrench. Slide the red wire with the ring connector off the stud and lay it aside.
Remove the front and rear mounting bolts from the alternator with a socket and ratchet. Three bolts hold the alternator in the car. Lift the alternator out of the engine compartment.
Position the new alternator on the mounting brackets and install the three mounting bolts. Tighten the bolts with a socket and ratchet.
Push the plug in connector from the wiring harness into the terminal on the alternator until the locking tab engages. Slide the red wire with the ring connector onto the “B” terminal on the back of the alternator followed by the retaining nut. Tighten the nut with a wrench or socket and ratchet.
Rotate the serpentine belt tensioner counterclockwise with a socket and ratchet to loosen it. Slide the serpentine belt onto the alternator pulley, then rotate the tensioner clockwise, applying tension to the belt.
Reinstall the negative battery cable on the negative battery terminal. Tighten the retaining bolt with a wrench.
