There is a blue wire on the TOD computer. Disconnect it and you are in 2wd. Dump 12v steady power and you are engaged in 4wd 100%. Use a 5 pin relay to switch control back to the TOD computer and you are back to stock operation. There are other wires that control the dash lights, wiring diagram is in the workshop manual, that I want to be able to override. Still working on the best way to wire that up without it getting super complicated.