The brake pedal on my 2200 will suddenly drop an inch as I am coming to a stop, the brakes will release slightly but the truck does stop, albeit with reduced grab. It drove local mechanics crazy. They changed master cylinders twice, pads,shoes, calipers, etc.

I finally drove to a dealer (130 miles) who fixed the problem in 10 minutes. He told me the sensor was covered with rust and couldn't "read" properly. As a result it thought my back wheels were locking up as I came to a stop and would release the rear brakes. They cleaned it up and it worked perfectly for two years.

This week, my local mechanic replaced a caliper and bled the brakes and now the ABS is acting up again and I don't want to drive the 130 miles again.
Does anyone know where the sensor is and how to clean it?

I believe it is located on your rear end pumpkin probaly has two wires coming from it.