ABS Light Question HELP PLEASE

I have a 99 Explorer that has the ABS light on. Where do I locate the sensors? How many are there? The brakes work fine. Thanks for your assistance.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.