Most likely, you have the “hot” and “ground” wires backwards.
I have an Gibson classic 57 humbucker witch has an really high output = 9K!! and its NOT an classic+ what I know, but installed it by iself in bridge position whith selector on treble it sounds thin, wery quiet and is humming slightly. What could be wrong?
Hi Sven, it sounds like you have a wiring problem. Most likely, you have the “hot” and “ground” wires backwards. Triple-check your wiring diagram that came with the pickup. If you can confirm 100% that the pickup is wired correctly, then try touching the hot / ground wires directly to a guitar jack, and tap the pickup. There should be a loud and healthy “Thud” that comes out of the amp when you do this. If not, then the pickup is damaged.