Jazz basses don't use a selector switch to control what pickup is active, they use two volume controls that allow you to blend the pickups together.
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EMG Select For P-Bass Pickup
Select pickups have hum-cancelling design with wide bandwidth and high output. "Blade" polepieces provide more uniform string-to-string response.
How to Wire a Fender Guitar DVD
We demystify your Fender guitar's electronics! Learn how to wire it cleanly for great sound.