Instructions for changing alternator on

The light comes on because it is not receiving the proper signal from the electrical circuit. Before you replace any parts take a 1/2 hour and some emery cloth and make sure that all the connections are tight and making good contact. Do the battery cables at the battery and the wires that attach to the alternator, including the plug-ins. Also clean up the ground wire that runs from the battery to the body. If the light is still on then get both the alternator and the battery tested. The alternator should read above 12.5 volts, preferably 13.5 to 14. It might be a new battery but get it "load tested". This is a measure of your battery's ability to retain voltage. A reading in the area of 11 volts after the test is an indication the battery is dying or not big enough to do the job. 500 CCA is a good size for a battery, less is working it harder and wearingit out faster. Hope this helps.