According to my resources there are two small wires. The brown wire is the charge indicator signal. The grey wire is the charge duty cycle controller circuit.
Some alternator will begin to fail with heat, as the alternator warms up parts inside the alternator will expand in side and loose good contact within the circuits and when it cools down the contact improves.
Check the large red cable electrical connections at the alternator and the battery terminal clamps are tight and not corroded. Make sure the belt tension is tight and not really loose. The belt is tensioned automatically by the tensioner pulley so it should be tight enough.
When the vehicle shows it isn't charging, open the hood and tap the alternator with a mallet (do this with the engine running) or the wood handle of the mallet and if this corrects the charging voltage, plan on replacing the alternator assembly
Thanks for the question
Tuesday, May 20th, 2014 AT 6:11 PM