My 05 LS has 104,000 miles on it. I was doing 50 mph down the road in 4H, then started hearing a whine....cycled through 2,3, D and it would intermittently change the whine. Stopped the car a few miles later, put it in park and realized the car was rolling forward. Put it in reverse and the car wouldn't move, just a metalic "zinging" sound coming from the tranny.

So I drive 5 more miles to get to home figuring I'm going to do some tranny work. Stop the car at the house, put it in park, (now in 2H).....it works. Put it in reverse, it works. Screw with it for 5 minutes cycling through all the gears, park, 2H/4H, etc. and it's like nothing ever happened.

Thoughts?????.....I don't believe that there isn't a problem going on somewhere. Really odd that it "fixed itself".

 

It sounds like one or more shift solenoids weren't working or there was a valve body malfunction (sediment?). There's probably some code stored that may shed more light. It probably "fixed itself" because you reset the PCM by turning it off and then on. Has the transmission fluid been serviced yet? Mind, if the fluid looks burnt, you won't want to change it with that many miles.