overdrive fuse keeps blowing. drive one and 2 shifts fine. 3 and overdrive dont work. had transmission checked it is fine. repair shop says it is electrical.

 

Figure out what year and model truck you have, and what model tranny. Then see if autozone has some diagrams on it. Go to their site, register, and then plug in your truck and go to repair info, repair guides, and then wiring diagrams. Look for the color wires that go to the overdrive solenoid on the tranny, and then get under the truck and follow these wires up, looking for melted or damaged wires.