Upper two are somehow used to tell the ecu you are in a top gear, and adjust tje timing or fuel delivery for more economical running, mainly to do with USA emisdions, especially stricter California.
Aussie deliveted cars had no need for this, dunno wether the ecu "read" these.
I treid using them to send false signal in order to overfuel engine for race use, nup, it reduces fuel, and alters timing the wrong way.
I ended up using other sensors signals into ecu to get desired effect. Blew four up though, trying!!
