Flashing OD light could mean a lot or simply nothing. My Winstar's (1996 3.0GL) was flashing on and off (especially in hot weather & on long drives) before I had the tranny rebuilt; and it still does, AFTER the rebuild (at Ford dealer). The tranny-doctor says it's the PCM. I am looking for a PCM and once I replace it, I'll report back; if the doc is right, OD light should stop flashing. If your car's tranny shifts ok then I'll keep driving until it dies; avoid long drives in case you get stuck with a dead tranny. Ford mechanic tells me, when OD light flashes, pull over, turn off, wait a minute or so and then turn back on. This becomes a pain if OD light flashes every hour or so; then I just ignore it. Good luck. | 
