yo,
That is da "Trailer Relay Box"
Here is the Location pic in 92-96; to the right side (when standing next to driver's side front wheel) of the Power Distribution Box,
whose cover is open;
miesk5 note, squeeze both sets of tabs together & lift cover off; only 1 Bosch style relay is in there
Source: by Froggmann (Ken P) at
http://www.froggmann.com/Images/ABSCut.jpg
&
Trailer & Camper Wiring Diagrams for 94 & 96 Bronco & Trucks
Source: by Ford via Steve83 (Steve, That dirty old truck) at SuperMotors.net
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Here is da 4-wheel anti-lock brake system (4WABS System) Wiring Diagram in 93-96
Source: by Steve83 (Steve, That dirty old truck) at SuperMotors.net

In the Box, you'll see a diode with the 4WABS main relay & 4WABS Hydraulic Control Unit (HCU) Pump Motor Relay.
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Another question: whats a good way to test the diode at slot 12 in the power distribution box and the #1 relay?
will bbl, I can't get my Comcast connection to speed-up