So I scored the entire Reverse Alert system from a 2003 Ex in the scrapper.

I got the Parking Assist Module, Speaker, Sensors, and button up front.

I got the entire harness under the rear bumper.



The harness in the bumper plugged into a connector on the main harness, I got that connector with about 10 inches of wire.

I got the Parking Assist Module with it's matching connector and 10 inches of wire.

I've already installed the button panel with the 4WD switch, the Defrost switch, and the Parking Assist button. The wiring was already there, just plugged into nothing (blue connector.)

Is the rest of the wiring there or am I going to have to build a harness?

 

It sounds like you have all the components connected? If you were able to find mating connectors for everything, I think you will be good to go. Ford, a lot of times on wiring, will use the same harnesses but just not install the components.

 

The wiring is there for most if not all the options offered as Ford seemed to have used a single harness to keep costs down.

For example, on my 2wd Excursion, converting it to 4wd wouldn't take much as the wiring for the ESOF is there. All I have to do is plug in the switch and module for the vacuum pump.