2001... Overdrive light flashes (not all the time) and starting to hold up before shifting.....took it to have coded (728) mechanic says could be sensor, spring, or 3-4 other things (100 to $1,500) can't afford for him to go 'investigating'.....anyone know much about tranny codes or where i can read up on them ?

 

Watch out when you search Google for "tranny codes". Make sure you stay away from image search!

Serious note - I have nothing to add.