2. Check the overdrive fuse. The overdrive fuse is located in the fuse box under the hood. Check the fuse to make sure that it is not blown.
3. Check the overdrive solenoid. The overdrive solenoid is located on the transmission. Check the solenoid to make sure that it is not damaged or disconnected.
4. Check the transmission fluid. Low transmission fluid can cause the overdrive to not work properly. Check the transmission fluid level and add fluid if necessary.
5. Have the transmission serviced. If the overdrive still does not work after checking all of the above, you may need to have the transmission serviced.