I want to use a wheel speed sensor to turn on a pump but the tachometer speed is slow less than 500 rpm’s. How would wire it

 

Welcome to AAC!

Please be more creative than "Help please". Imagine if every thread began with the title "Help please".

A better title would be "Need help with speed sensor on pump".

 

It would also be a great help if you post any and all details of the present devices and what you are interfacing with.
Everything is guess work from your post.
Honeywell have a gear tooth sensor as used in automotive applications if a device is needed.