better off buyin a new trans, cause its gonna cost ya a hellafied amount to fix.Most of the times its impossible to fix them, they are usually replaced. I had a problem with mine gotta manual trans, just so happened that the ecu was fried bought a new one works just fine. Start off small like checking the ecu if good - look in the engine to see if any of the connectors goning twards the trans are chipped, rotting away, loose, cracked u get the idea, if good then take to a shop the worse thing they can tell you is you need a new tranny