I have an 00 Dak with a 4.7 and the overdrive wont shut off.I know the bulb is working when I turn the key on it lights up.I just bought this truck then realized the problem so I picked up a Hanes for it and of couse it dont say JACK about the trans.I will be pulling my boat so I really need to be able to kill the OD when I want to.Any ideas?

Go to http://www.alldata.com/ they have good online manuals with electrical wiring diagrams. Cost $25.00 per year with a discount for the second vehicle.
Print the wiring diagram.

If your vehichle has the gear shift on the steering colomn and the on/off is on the end of the gear shift it could be the wiring connection inside. You can take the gear shift off and check the connection.