Don't shoot me, Chivy ?

Without a wiring diagram, you are just beating your head against the wall. My 98 Ranger, as an example, has a built in "converter" so you can use integrated stop/ signal lamps on a trailer, even though the pickup itself has separate turn and stop lamps. Some moron before myself didn't know that (the connector was bagged up in the jump seat compartment) and installed a Valley converter ---meaning he hacked up the wiring, and the aftermarket converter actually failed.

Don't guess. Get a diagram, or at least a Haynes/ Chilton manual.