So what does this switch do? It totally bypasses the volume and tone controls. This comes in handy for soloing because, you can go from a quiet, mellow sound to a screaming, biting, full volume, full tone attack and just as easily return to the previous settings without the need to touch the volume or tone controls.
Actually, you can have all the volume and tone settings at zero, but when the solo switch is “on”, it’s just as if you had everything set to “10”. (Actually, the sound is a little bit brighter than “10” because even at their maximum settings volume and tone controls still put a “load” on the output signal).

This circuit is rather easy to wire and the ‘before’ and ‘after’ diagrams are helpful in figuring out how everything will get connected. Just proceed carefully and you should have no problems.

That’s all well and good if your guitar only has one volume and one tone control.
However, we know that all guitars are not made the same. So, we’ll show other diagrams that can be used in two very popular guitar circuits.

This section deals with wiring a “Solo Switch” for a guitar with the circuitry of the Fender Stratocaster™ or one of the countless copies manufactured with the same design. If you have a 3 pickup guitar (usually 3 single coils), that has one “five-way” switch, one master volume control and 2 tone controls, this is how to wire a solo switch into it.

Diagram 1 is the way your guitar is currently wired.
Diagram 2 is a detail of a small section of Diagram 1. This is where the rewiring has to be done.
There is a jumper wire on the five way switch that goes from the upper left lug to the lower right. Cut this wire and carefully remove ¼” insulation from the 2 ends. Do the same with the wire from the middle terminal of the Volume Control. Solder some wire extensions to these 4 points, making sure these wires are long enough to reach wherever the solo switch will be mounted. Tape the 4 solder connections.
Now, solder these four wires to the DPDT switch making certain that each wire goes to the corresponding terminal. (The wires and terminals have been given letters to make your job a little easier).
You have now finished. Recheck and test your work until you are certain that everything’s wired okay.
Plug it in and enjoy your latest guitar modification.

Due to the complexity of the wiring of dual volume and tone control guitars, it is not possible to bypass 2 volume controls, 2 tone controls and 2 capacitors with just one DPDT switch so some compromise had to be made.
One disadvantage is that, unlike the other 2 circuits, this “Solo Switch” can only activate the bridge pickup.

However, one advantage is that it will bring the bridge pickup into the circuit no matter what position the pickup selector is in. (This does not apply to the previous 2 circuits).

Still, if you want a true solo switch, go to the next section.

The above diagram is the circuit for the Gibson Les Paul™, the Gibson SG™ and the many copies of these guitars. Basically, if you have a guitar with 2 volume and 2 tone controls, it would probably be wired in just this way.
For this modification, you will have to cut the wires at the positions indicated by the red arrows.
Solder 4 extension wires at these locations.
To make certain that you wire the circuit properly, the detailed graphic below is much easier to follow.

Okay, if you have scrolled down here, you are a purist who will settle for nothing less than a genuine solo switch that can bypass all four potentiometers and both capacitors. As you probably thought, there must be a “catch” right?
Actually, there are a few.
Instead of a DPDT switch, now you must use a 4PDT switch, which is a little harder to find and more expensive than the DPDT.
The 4PDT switch has twice the terminals of a DPDT. (larger switch space and more soldering)
Instead of two connections for cutting and soldering wires, you now have to deal with four. (see diagram)

The above diagram is the circuit for the Gibson Les Paul™, the Gibson SG™ and the many copies of these guitars. If you have a guitar with 2 volume and 2 tone controls, it would probably be wired in just this way.
For this modification, you will have to cut the wires at the four positions indicated by the red arrows.
Solder eight extension wires at these locations.
To make certain that you wire the circuit properly, the detailed graphic below is much easier to follow.

Using electrical tape, insulate the eight solder connections you just made.
Now, following the letters exactly, solder the eight wires to the 4PDT switch.
When you are certain the wiring is correct, close up the guitar, plug it in and try out that new solo switch you just wired in.