gilles weilb-
Welcome to iRV2!
I looked it up, and it appears your coach is a Class A built on the Ford F-53 chassis. Please confirm.
If that is the case, there should be a Ford six-pin connector under/inside the dash. It will be grey (or brown, I forget which), have two rows of male pins in a female housing, and five wires: red, green, blue, white and brown. At the rear of the coach is more of a crapshoot. The blue brake controller wire may be attached to the correct pin on a
five-, six- or seven-pin hitch connector. If it is not attached to the connector, it should be in the wire loom under the coach, about four to six feet from the rear of the coach.
Most people find the search for the under-dash connector a challenge. Start with that, and let us know how you do.