From what I've read elsewhere, it has indeed reopened. They resurfaced the roads, painted everything, and put some new monitors in the preshow rooms. Also , someone on another board said that they upgraded the software that runs the ride, so hopefully there will be less breakdowns. They haven't done anything about the audio doesn't work sometimes-- I rode once last year with no audio whatsoever, which meant no engine sounds or squealing tires or voices-- just silence. It was pretty boring.
I talked to a CM once who said that Test Track "breaks down" so often because there are so many variables in play. It's probably the most technically complex attraction at WDW, hence the frequent down time. I'd be curious to find out if Journey to the Center of the Earth at Tokyo DisneySea breaks down that often, because it uses the same ride system.