automatic overdrive failure

89 lincoln continental v-6 overdrive not working. Posible causes?:(

This is the front wheel drive Lincoln with the 3.8L V-6??

yes

Unfortunately, this is the same transmission that was in the Taurus/Sable line. It is highly likely that the transmission is on it's way out. The bright side may be that it could be the cable is too tight and out of adjustment, but this should be acompanied by real strange shifts, generally very high rpms before it bangs the next gear.