Basically the gear limit switch does exactly that, it sets the Maximum gear the transmission will shift into. If you set it on 5, it will still start out in 1 and shift up or down through the gears normally, it just won't let the transmission go above 5. You can also use it to ensure compression braking going downhill by setting it in a lower gear. Final point, in Tow mode shifts are more aggressive but the limit switch still works the same way. Basically works exactly the same as the old column mounted gear selectors on earlier automatics. I like the way it works much better on my 8 Speed than the way my Cherokee works on the 8 speed in manual mode, where a manual gear selection always drops the gear to 1 and you have to manually upshift from each stop, and the transmission will not downshift idf if you step on the gas. If you have 7 selected, that is where it stays even if you matt the gas. Very poor system design on the Grand Cherokee.