What happens by putting one side of a capacitor to ground and the other size to the hot terminal of a pickup?
Depending on the value used, if one side of a capacitor is connected to ground and the others to the hot terminal, the higher frequencies will be cut. If you put one side of a .05 mfd. capacitor to ground and connect the other size to hot, you would reduce the brightness in the pickup basically the same as if the tone control on your instrument was turned to zero.