Hi...anybody know anything about a factory 3-speed with an overdrive (behind a 390ci)? Mine won't shift into overdrive. Kickdown switch seems to work. Maybe my solenoid? My truck is a 1966. Thanks ahead of time.

 

I'n the past two months I took a crash course in overdrive diagnosis and repair. I have learned guite a lot and got a lot of great info like wireing diagram ect..from the great folks on this site. This group is a God send! First you want to check the fuse mounted on the firewall relay. If it is blown I would look into why instead of slapping in another and forgetting about it. Probably a wire worn bare somewhere around the tranny if the fuse is blown. You can check the whole system by disconecting the governor wire and grounding the hot side coming from the harness. This wire is on the right hand side and I believe the wire is black. When you ground this wire with the switch on you should hear the firewall relay and the solenoid mounted on the left side of the tranny.

When I did this to mine I heard the relay click every time but the solenoid only activated after several relay clicks. This told me to clean the relay. You can remove the cover and run emery cloth through the points inside. Also clean all the spade connections well. If you dont hear the solenoid you can take a set of jumper cablesand a battery and connect - to the frame and + to each of the wires seperately. You should get a reaction out of only one of those wires. If you get nothing take off the cover and spray everything down with electric motor cleaner and clean up the points in there as well. You may be able to bring it back to life.

I think most of the cleanup stuff I mention would be a good idea for anyone who wants a dependable OD. Mine works slick as a button. Kind of neat winding second up to 28 and letting off the gas and getting another gear.

Oh! make sure your dash handle is working freely and the push/pull end down under is not kinked.

Hope this helps. Let me know if you need a diagram.

 

Please...a diagram would be great. My e-mail address is, chews32@earthlink.net. Thanks for the help. I'll try and get to it this weekend, that's if I don't eat too much. Have a great Thanksgiving.