Begin with the symptom
On many two-volume passive guitars, selecting both pickups and turning either volume fully down silences the whole output. That can be normal operation rather than a failed pickup or selector. The two controls share a connection at the selector in that position. A volume wiper at the grounded end of its track can therefore ground the shared signal connection.
Test the two single-pickup selector positions first. If each pickup works alone but the combined position goes silent only when one volume reaches zero, record that behaviour before assuming the harness is faulty. If a pickup is silent in its own position, investigate that separate fault rather than explaining everything as volume interaction.
Follow terminals, not diagram orientation
In the conventional volume arrangement used in Apparition terminal references, lug 3 is the signal-input end, lug 2 is the wiper/output and lug 1 is the grounded end. These identities describe the pot with the stated reference orientation. Confirm the actual part orientation, and keep its metal casing separate from the resistive track terminals.
For two conventional volumes feeding a selector, the selector joins their wiper outputs when both pickups are selected. At minimum, one wiper reaches the grounded track end. That creates a low-resistance route from the shared output to ground. The practical result follows the connection topology, not the pot brand or an unexplained defect.
What the independent arrangement changes
A commonly used independent-volume arrangement connects the pickup to the wiper and takes the outgoing signal from the opposite signal-side track end, with the other track end grounded. This exchanges input and output connections relative to the conventional arrangement; it does not rename the wiper or alter physical lug numbers.
At zero, the pickup-connected wiper reaches ground, while the outgoing connection remains separated from that ground by the track. The other pickup is therefore not simply shorted through that control. Independent means a useful change in the zero-volume interaction. It does not mean the two sources or their loads are completely isolated.
The trade-off is still an electrical network
Changing the arrangement also changes the impedance seen by the pickup as the knob moves. The response and useful sweep can differ from the conventional circuit. Tone connections and treble-bleed placement also need to match the intended topology. Moving a single wire while retaining every other assumption can produce confusing results.
Modern versus 50s tone wiring is another choice. It concerns where the tone network connects relative to the volume control and should not be treated as a synonym for independent volumes. Decide separately which interaction and tone connection you want.
A bounded bench check
Disconnect the guitar from the amplifier and record the original wiring before making changes.
Identify each volume wiper and track end with the actual part drawing or an isolated resistance test.
Compare the signal and return paths in each selector position, including both volumes at zero and full.
After continuity checks, compare control behaviour with the same cable and amplifier settings; do not treat a drawing as a promise about perceived sound.
Use the existing Les Paul control and lug guides for the conventional harness first. The Generator and Signal Forge links are references for their explicitly supported topologies; an independent-volume modification is not automatically covered by the current model.
References and scope
StewMac: volume-pot wiring and independent control
Seymour Duncan: Les Paul wiring variants
This guide describes passive instrument electronics. Verify the actual part documentation and disconnected circuit before changing a connection. Tool links below are for supported configurations and do not imply that every modification in this guide is modelled.
Further reading
Manufacturer context to read alongside this circuit reference: