Charging troubles

[timo pajala]

I have lc9 engine from 09 truck with 5.3ls. It has 4 wire pigtail but only two wires go there,Grey and Brown. How does it has to be wired to get it chargin? I know the ecu controls the charge i think but mine does not charge at all. I also connected my fan positive wires straight to the alternator, is that bad or ok?

[timo pajala]

Alternator was bad even it was new. I bought new one and wired it thru ignition switch yo alt light and then to L port in alternator and it started charging..this is a new 105A truck alternator