Even auto mechanic can't figure why fuse #20 keeps blowing. OD light was blinking, check transmission flash and car is bucking. Replace fuse and it is better. But could blow in a twenty min ride or last a day trip. Any ideas?

 

The overdrive light flashing tells you there is a problem with/ in trans. Don't know what type vehicle you have , but check the connections at the trans plugs and look for corrosion. That will be a good start.