Someone suggested this here and I want to thank you and pass on the good information. Obviously you want to verify that your overdrive relay is functioning correctly before proceeding with this precedure. (By the way, if you just hear the relay click, that does not mean that it works and the correct amount of amperage is being sent to the solenoid.) If you don't hear your overdrive solenoid click when a friend pushes the button on the shifter and you listen under the car near the overdrive solenoid, try this after you verify the correct signal to the solenoid with a test light. Check the wire to the solenoid as they can get eaten by heat and oil from a leaky rear main seal. Remove your overdrive solenoid and spray brake cleaner through it using the small straw on the can. You will see two small holes where transmission fluid passes through, thats where you spray. Then hook 12 volts to the wire and the body to ground. You should hear it click. If not try disconnecting the 12v and reconnecting it repeatedly. Then spray more brake fluid through the holes. I had to do this several times to get the solenoid to work properly. Then install your solenoid and make sure you have the o ring properly seated before you torque the 2 12mm screws. I have a feeling a lot of solenoids were replaced instead of just cleaned and reinstalled. I believe the solenoids are around 100 bucks so this is worth a try before buying a new one.