Recently I've noticed that during the night, lights on, when the truck goes idle, lights go a little dim, and the voltage goes around 12 volts. The alternator has been rebuilt recently. Is something wrong with the charging system???

When I've seen this it was the battery cables.
When I've seen this it was the battery cables.
You have the 90amp? I didn't think the 80 could be rebuilt.
Like landtank said check your cables, that was my culprit.
The battery came with the truck, so I have no idea how old it is..![]()
I think you may have identified part of your problem there. You have had that truck for a while now haven't you?