OD light begins blinking when stopped in traffic. Transmission slips slightly when taking off but shifts properly most of time. the speed sensor was replaced along with alternator (mechanic said alternator output varied), did not fix problem, Ford dealer mechanic said new speed sensor was ok but abs unit sending irregular signals. Later said electrical noise caused by alternator was the problem. Installed new alternator - no fix. service computer shows indicated speed at around 15 mph will vehicle is on service rack with engine running (?) Unplugged alternator and problem disappears. When OD light doesn't blink transmission operates fine.

So far no fix found in 2 weeks.

Was on the way to hunting trip in NW CO with 32K miles. O/D light started flashing at Eisenhower Tunnel. Coasted into dealership at the bottom of hill. I bought this truck used and luckily had purchased a bumper to bumper warranty from my lender. Had to wait for the diagnosis and a rental car, first one was too small (hunting camping gear) then had to wait for hunting party. I was supposed to be early to setup camp! Had to travel back (5 hours, one way) to pick up my truck a week later. I paid to install synthetic fluid and have had no problems since then. Now at 130K miles.

Huntington Ford again. 3rd major trans issue in 7 years on a truck that is supposed to be Super Duty.

Ran the truck in 4 Wheel Hi during a snow storm. 3 trips, first two were 4 miles round trip. 3rd was 8 miles. The OD off started flashing on the return trip (about 3 miles to go). Trans would not shift out of 3rd gear. Disengaged 4 WH back to 2 WH. By the time I was within a mile of home, the service engine light was on. Switch is located inside the trans case, so it is 450 to drop the trans and 540 for the part. Great timing. Took it in on a Tuesday afternoon, should get it back Friday morning. Atleast they pick up half the rental cost this time.