2005 M7 Fuel Selector Plug

Just a quick question...

A buddy of mine owns the above-mentioned sled. He doesn't have the owners manual. What does plugging together or un-plugging the wiring harness pigtails accomplish for fuel settings?

I tried looking for an owners manual online with no luck, but I see from reviewing the online Cat parts manuals that this feature is gone after 2006??? What changed or is there now a plug instead of the pigtails???

Thanks...