4×4 issue (help)

Hi all and to anyone that can help.

I have a 04 Sportsman 700efi and the 4×4 won’t engage properly. When I switch it on the 4×4 icon shows on the dash, but when in H or L the front wheels don’t turn. However when I put in R with the( switch on or off ) they turn with full traction?

I did a voltage reading of the diff wires ( Gray and brown) connection point both top and bottom of the point, with the bike running(switch on) it read 10.56 volts. then I tested the battery and it was around 11.59 volts.

And at times the battery light and speedo flashes at idle.
Guessing I may need a new battery as well

Thanks
La-012015