What's up guys! OK so my 7.3 is running good.... but today it started to not go into overdrive . It shifts 1 through 3 just fine , automatically and manually. But it will not go into overdrive so the rpms stay around 2100 at 50 mph ... is there a relay or fuse that tells the overdrive to kick in and shift???

 

Also I was watching some videos on overdrive switch and I do not believe its the wiring on the column because the overdrive light still turns on and off with the press of the button...... if that helps to know

 

There is no fuel or relay involved. You need to get the codes read. The places that read codes free cannot read these codes.