For a YouTube video of this mod, click here.

The typical 3 single coil guitar has five switching options – neck only, middle only, bridge only, neck and middle in parallel and middle and bridge in parallel.
This modification allows a 3 single coil guitar to have two additional switching options – neck and middle in series and middle and bridge in series.
S2 is a double pole double throw switch that changes the switching from regular 5 way switching to series switching.
S1 is a single pole double throw switch that selects neck and middle in series or middle and bridge in series. In essence, it is switching from something similar to a neck humbucker arrangement to a bridge humbucker arrangement.

IMPORTANT: The series sound will only work if the 5 way pickup switch is in positions 1, 3 or 5.
Switches S1 and S2 have no center position.

You might have noticed that turning down the volume of your guitar causes a loss of high frequencies. Some guitar players just accept this but if you want to do something about it then these 3 circuits will probably interest you.
Diagram 1 is the easiest of these 3 modifications and it only requires one capacitor and two solder connections. The value of the capacitor in that circuit is usually about .001 microfarad (1 nanofarad or 1,000 picofarads). You may wish to choose a lower or higher value because after all, it is your guitar.
With this modification, all you have to do is solder the capacitor to those two terminals and that’s it.

That circuit has one problem – as the volume is turned lower, more of the higher frequencies will predominate, even to the point where the guitar starts to sound very “tinny” as the volume approaches zero.

Diagram 2 In this circuit, a resistor is connected in parallel with the capacitor, and as the volume is turned lower, the higher frequencies are not as dominant.
As for the values of the components, there are different opinions but the most popular is the one suggested by Seymour Duncan who recommends 100K for the resistor and .002 mfd for the capacitor.
The problem with this circuit is that it affects the taper of the volume potentiometer.

Diagram 3 Here, a resistor is placed in series with the capacitor, which seems to solve the problem of the volume pot taper and the “tinny” sound. There are different opinions for the component values but most people agree with Australian pickup manufacturer Chris Kinman who suggests using a 130K resistor in series with a .0012 mfd capacitor.

Before you decide to rewire your guitar based on Diagram 3, keep in mind that it might not be the solution you need.
There are three different treble bleed circuits and many different recommended values for the components. Also, guitars have different pickups (high output, low output, humbucker, single coil) and different potentiometer values (250K, 500K, 1 Meg). Then again, the tone of a guitar through one amp might be greatly different from that of another amp.
And the final decision is up to you.

This diagram shows two pickups wired in stereo.
The switch is a Single Pole Double Throw Center ON type.

This diagram shows a tone control that has a switching option for choosing 2 capacitor values. The switch is a Single Pole Double Throw (SPDT). Suggested values for the capacitors would be .02 and .047 mfd.

Switching for Neck / All 3 / Bridge

The switch used is a Double Pole Double Throw (DPDT) Center On switch. Go to this page, scroll down to DPDT Switch, and look at Diagram C. This is the type of switch you want to use.
The wires shown from neck pickup, etc are the “hot” wires. The ground wires are not shown but they would be connected to each other and connected to the output ground.

Look at this diagram to see how this works:

Switching for Neck / Middle / Bridge

The switch you want to use for this circuit is a DPDT on/on/on switch. Go to this page, scroll down to DPDT Switch, and look at Diagram D (a totally different type of switch than the one used in the previous diagram).
The wires shown from the neck pickup, middle pickup, etc are the “hot” wires. The ground wires are not shown but they would be connected to each other and connected to the output ground.
Look at this diagram to see how this works:

This modification requires that the guitar have 3 humbucking pickups, each of which is wired with a series/parallel switch.
Yes, it really has 94 different pickup switching arrangements.
Granted, each of the 94 sounds do not sound totally different from each other.
However, recently, “compound” pickup arrangements are becoming popular (for example, one pickup in parallel with the other 2 in series). This switching arrangement allows you to try all possible arrangements (compound and otherwise). In this way you can decide which ones you like.

Someone named Jeff submitted his variation on the 94 sound wiring option. His wiring uses single coils instead of humbuckers and 5 SPDT center off switches in place of the 9 SPST switches.
He also added 2 DPDT switches for “out-of-phase” tones and a single pole triple throw rotary switch for selecting different capacitors.
This results in 17 different pickup combinations(see table below), with 22 additional sounds enabled by the phase switches on the neck and bridge pickups and all of that multiplied by the 3 tone circuits, producing an incredible tone monster.

The above diagram shows a 3 pickup guitar with a phase switch for each coil. (These could either be single coils or humbuckers.) This drawing is based on John Atchley’s “Individual Pickup Selection” modification.
Each switch is DPDT center OFF. (Actually, at most, you’d just need 2 phase switches to get all possible phase combinations and you could replace any one of the switches with an SPST. Just something to think about.)
Since, the switches are center off, you get the 7 choices of each single coil, middle & neck, middle & bridge, neck & bridge and all 3.
Out of phase sounds have their place, but being able to get all possible in and out of phase combinations may not be worth the effort. Even John Atchley, the designer of this circuit has said “I’ve quit building these particular modifications because I didn’t find the phasing to be that tonally useful.”
It does seem to be overkill regarding phasing, but the idea of using 3 SPST toggles to control the pickup selection is very convenient. If you want to see those diagrams, go to Page 1 and look at “3 Single Coils Wired In Parallel” and “3 Single Coils Wired In Series”.