i just had the same thing happen to me...didn't count the power light flashes though.
i just got my tranny replaced and when they put on the speedo gear (plastic btw) they must not have attached the retaining clip properly because it popped off.
my speedo stopped, then a few minutes later, the check engine light came on.
anyway, they ended up replacing the speedo gear and clip and had to drain the fluid--the plastic gear was chewed up by the other gears. to get to it, however, is another problem---they had to drop the tranny because of it's location.
a week later, i was back on the road---in fact, i just picked it up tuesday.
when they were testing it to find the cause, they mentioned that the speedo rod (don't know the technical term) just spun freely.
good luck...
toby