Back when Strats were first made, they came with a 3-way switch (one position for each pickup), but some savvy guitarists soon realized that if they moved the switch into a position midway between two of the “official” positions, they could get two of the pickups to turn on at the same time, resulting in new sound options. This happened because the switch was what is known as a “make before break” switch, which means it touches the next contact before disconnecting from the previous one. It wasn’t easy to keep the switches in these in-between positions and guitarists often resorted to sticking matchsticks, etc., into the switch slot to hold them in position.
Seeing how customers were doing this, Fender eventually started installing 5-position switches. Note that these were still really 3-way switches, just with a couple of in-between positions added on so that matches were no longer required to hold the switch in those positions.
Also of note is that the switch is “dual pole”, which means that it is basically two switches in parallel that move at exactly the same time, without being electrically connected to each other. If you take a good look at the switch below, you will see that there is a second row of contacts on the other side.
Looking at the photo of the switch a couple of images back, you can see that there are four contacts on the side facing us (and four on the other side that aren’t so easy to see). Of the four on this side, the left-most one is the “common” contact, which is to say that it is always connected. The three contacts to the right correspond with the three main switch positions (with the additional two positions being in-between 1 & 2 and 2 & 3 respectively). The other side of the switch has a similar setup.
Now given that there are only (normally) three pickups, and the switch has three contacts on each side (in addition to the common contact), you may be wondering why we need two sets of contacts in the first place. Well, this is so that you can have a bit more freedom when it comes to choosing how to control the volume and tone of each pickup. For example, with standard Strat wiring, the volume pot controls all three pickups, whereas the two tone pots control one pickup each (with the bridge pickup having no tone control at all). Older Strat versions had one of the tone pots controlling two of the pickups at the same time (and there are many more options too!)
Here’s how the switch would look from below. Rather than numbering the pins–which I think can be confusing given that there are 3 pins (not counting the common pins), but five positions—I’ve named them B (for bridge), M (for middle), N (for neck) and C (for common).
Again, remember that you also have two additional positions, as mentioned previously, in-between bridge and middle (so pins B and M would both be connected to C at the same time), and in-between middle and neck (so pins M and N would both be connected to C at the same time).
As for the other side of the switch, despite the fact that the pins appear to be in a different order, they still work the same way, so when the switch is in the Bridge position, the left-hand pin B is connected to the left-hand pin C, and the right-hand pin B is connected to the right-hand pin C.
I hope you’re still with us here. The above can be a bit of a brain melter, but once it clicks it makes a lot of sense.
In an effort to make this as simple as possible, here’s what a standard Strat’s wiring looks like just around the switch itself (remember that there are many, many ways to wire up a Strat and this is just one of the more common ones):
Without going into too much detail about how the tone controls actually work (that’s for another day), I’ll try to walk through how the switch works as clearly as I can.
When the switch is in the neck position, left-hand pin N (neck) is connected to left-hand pin C (common). This allows the signal from the neck pickup to pass to the common pin on this side of the switch. Since left-hand pin C is shorted to right-hand pin C, the signal from the neck pickup continues to right-hand pin C, where it then goes to the volume control. Additionally, right-hand pin C is currently connected to right-hand pin N, allowing the signal from the neck pickup to ALSO travel to the neck tone control.
When the switch is in the middle position, left-hand pin M (middle) is connected to left-hand pin C (common). This allows the signal from the middle pickup to pass to the common pin on this side of the switch. Since left-hand pin C is shorted to right-hand pin C, the signal from the middle pickup continues to right-hand pin C, where it then goes to the volume control. Additionally, right-hand pin C is currently connected to right-hand pin M, allowing the signal from the middle pickup to ALSO travel to the middle tone control.
When the switch is in the bridge position, left-hand pin B (bridge) is connected to left-hand pin C (common). This allows the signal from the bridge pickup to pass to the common pin on this side of the switch. Since left-hand pin C is shorted to right-hand pin C, the signal from the bridge pickup continues to right-hand pin C, where it then goes to the volume control. Additionally, right-hand pin C is currently connected to right-hand pin N, but right-hand pin N is not connected to anything else, the sound is unaffected by any tone control.
Remember that we also have those two additional in-between positions, but all that happens there is that everything is true for both positions either side of it, so for example in the in-between position between the neck and the middle pickup, everything I wrote about the neck position AND everything I wrote about the middle position is true.
Finally, in addition to a standard Stratocaster 5-way switch, you can also get import types, which look more like this:
Note that these are just wired up in the same way as the switch that I’ve already been describing, except that the pins are laid out a bit differently. In the above image, the pins are numbered (left to right) 3,2,1,0,0,3,2,1. These represent the following positions:
3 – Bridge
2 – Middle
1 – Neck
0 – Common
0 – Common
3 – Bridge
2 – Middle
1 – Neck
Finally, if you want to get all fancy with your wiring, you can get “super switches”, which have many more contacts, allowing you a much greater range of wiring options. Here’s an example of one below: