I've been installing a Gibson 500T pickup in my bandmate's Les Paul Studio. It's going in the bridge position. The old pickup (and the neck pickup) are Guild XR-7's. He has a habit of anchoring his pinky on the edge of the pickup, and apparently damaged the winding on one of the coils. The 500T installation went smoothly and the wiring is pretty straight-forward. My question is about how the Guild pickups were wired. Whoever did the installation, snipped the 4-wire pigtail and connected to the original 2-wire cable n the pickup cavity. The tied the two positive leads together but only connected one negative lead to ground. The other is just snipped and not connected to anything. Both pickups were wired this way, so it's intentional. When you tap on the pole screws, one coil is hot, the other is much quieter. I'm trying to figure if this wiring configuration is simply a split coil or whether the disconnected (-) wire does something different. I'm thinking it might be to add windings for a P-90 sound. I didn't test for north-south, but the Guild wiring is [Coil 1] White (+) Green (-) [Coil 2] Red (+) Black (-) Right now it's wired: red & white → (+) to controls green → (-) to ground black → (-) disconnected. The pickup does sound sweet and quite crisp for a neck pickup. The 500T wired in series was a bit too much of a contrast. I ended up wiring it in parallel for a more balanced sound. I'm trying to talk the owner into letting me install a pull up pot switch so he can have it both ways... Anyway, I'd appreciate if anybody could enlighten me as to the logic behind the way the old pickups were wired in.