can i trick the tranny?

[JLHollowX13]

so i was thinking today, can i trick my transmission into thinking i need awd? maybe i should start out with whats going on, and probably everyone that will reply to this knows whats going on. but anyway, my speedo doesnt work, and consequently, neither does my awd. it seems that my speedo gears inside the differential are toast, so i was thinking, is there a way i can rewire something to make my transmission think it should split the power 50 50. maybe rewire something that has to do with the speedo obviously, but maybe have a switch that i just have to flip, and it goes to 50 50, and when disengaged just goes back to how it is now. im not sure if this is realistic, but i figured it could be cheaper than fixing the problem for now, and id still have my awd when i need it. if im correct, the way the awd works is if the front wheels are spinning faster than the rear, it engages the awd to compensate for the difference and give the extra traction. if i could just trick my tranny into thinking my front wheels were turning faster by flipping the switch, then my awd would engage. any input would be very much appreciated. just trying to think of some cheap, temporary solutions. thanks!