Overdrive failure

1993 MERCURY COUGAR
180,000 MILES • 5.0L • V8 • 2WD • AUTOMATIC
Avatar
JEFFERY T.
  • MEMBER
  • 1 POST
When in overdrive RPM go high around 40 mph. Will not shift. Does not do it in drive only overdrive.
Dec 4, 2018 at 12:14 AM
Advertisement
Avatar
STEVE W.
  • CERTIFIED EXPERT
  • 15,113 POSTS
That car should have an AOD transmission. It uses a mechanical cable to the transmission to control the shift points. However if it shifts fine but loses only overdrive it is likely time for a rebuild as the most common reason for this is a worn or damaged overdrive band inside the transmission. This is indicated by the higher rpm as it shifts into overdrive. The band is slipping.
Dec 7, 2018 at 11:11 PM