The alternator in the Pontiac Grand Prix connects to the battery and the rest of the car's electrical system. If the alternator malfunctions, the electrical system will drain the battery. If you have problems keeping the battery charged or if you notice that the headlights are dimmer, the alternator probably is failing and will have to be replaced.
Disconnect the negative cable from the battery using a wrench to loosen the terminal nut. Some engines have a cross-brace; if your car is one of those, remove the bolts and take out the cross-brace.
Remove the mounting bolts from the coolant reservoir and move it off to the side. Do not disconnect the reservoir hose.
Turn the adjusting bolt counterclockwise with a socket and ratchet and lift the belt off of the alternator pulley. Unplug the voltage regulator harness from the alternator. Remove the electrical leads from the alternator using a wrench to remove the nuts.
Remove the bolts from the alternator with a socket and ratchet and pull it off of the engine.
Put the new alternator on the engine and tighten the mounting bolts with the socket and ratchet. Connect the electrical leads and tighten the nuts with the wrench. Plug the voltage regulator into the alternator.
Attach the coolant reservoir to the car in its proper location and tighten the bolts with the wrench. If your car has the cross-brace, reinstall it and tighten the bolts with the socket and ratchet. Connect the battery terminal and tighten the terminal nut with the wrench.
