Small Button Under Dashboard 1989 F:250?

So i own a 1989 Ford F:250 gas 7.5L 460 engine. So i found this have little black push button under my dash that tries to turn engine over(like when turning the key to start) but it doesn't start the engine it just keeps trying (I think)? It would be fantastic if someone could inform me on this.

It is likely a "hot wire" switch to the starter. Put the key to On, shifter in Park and press the button and see if the truck will start.

It's to activate the starter and pump the oil BEFORE firing up the engine using the regular key, so the engine is lubricated after being parked for a long time. Otherwise all the oil will have drained into the sump and the engine will suffer horrific wear if fired up to fast idle speed right away. Perhaps the truck was used only rarely because it's a fuel hog, so spent weeks parked between being driven only rarely. Or perhaps the ignition switch or park/neutral safety switch is defective, so this was a way for the previous owner to bypass those switches and activate the starter with the black button.

You'll have to ask the person who put it there. It's NOT a factory installation.