The 1999 GMC pick up came with several engines: 4.3-, 5.0-, 5.7- and 7.4-liter. The process to change the alternator is the same for all four engines. If the alternator is not putting out enough of a charge, the battery will eventually die and the vehicle will not start. If the battery is dead, the alternator must work harder to try to keep it charged, which could damage the alternator. Make sure the battery is fully charged and holds a charge before you condemn the alternator.
Instructions
- 1
Disconnect the negative battery cable and set it aside, making sure it does not touch metal. Unplug the alternator wiring harness connector. Remove the power wire from the back of the alternator using the appropriate wrench. Screw the nut back onto the post so you don't lose it.
2Rotate the accessory drive belt tensioner toward the center of the engine to loosen tension on the belt. Lift the belt off the alternator, and let it to remain on the rest of the pulleys. Allow the tensioner to fall back into place.
3Remove the alternator retaining bolts, then remove the alternator from the engine compartment.
4Bolt the new alternator into place. Tighten the right bolt to 18 foot-pounds of torque and the left bolt to 37 foot-pounds of torque. Rotate the accessory drive belt tensioner toward the center of the engine, then slide the belt over the alternator pulley. Allow the tensioner to gently rotate back into place.
5Plug in the wiring harness connector. Reattach the power wire and tighten it to 71 inch-pounds of torque. Reattach the negative battery cable.
