2004 Silverado 1500 5.3l.
I recently replaced my alternator because the bearings in it went out.
I have noticed that the new alternator stops charging at 3000rpm and higher. The original one did not do this. Did I buy a bad alternator? Cheapest one from advance auto parts. Any help is appreciated.
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https://i.imgur.com/SnzhDh0.jpg this test please… using a multimeter…
post results by number…
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that is a rare failure mode…
this voltage drop test sequence tests the electrical connections…
2004’s have had issues with the IGN A and IGN B wiring from the bottom of the fuse block to the wiring harness terminals… i have run across this many times… this can cut off power to half the ignition switch… this test requries a E-4 torx socket to remove screws holding the steering column shroud on… a test light to probe the electrical connector on the bottom of the ignition switch…
both red wires should have power in every position of the ignition lock cylinder…
the Thick white wire should have power in all positions except LOCKED… Off, Run, Cranking, Run and Off…
the Pink wire should have power in the Run Cranking and Run positions…
the thick Orange and thick Brown wires should have power in the Run position… Not while cranking and again in the run position…
2 of the 3 wires in the alternator plug in connector go to the computer. as the alternator output is computer controlled… . one goes to the brake system???
this is a strange failure…
belt tension…???
Most likely the new alternator is junk. I’ve seen this happen on similar gm models at higher rpm’s do the same thing.
