You will have to take it to a shop (not Autozone) and have them read the code. This code is not accessable by using the standard scan-tool. Those tools can only read codes if the CEL is illuminated.
Normally though, this means that "something" electronically is going screwy with the tranny. What could it be? Pick a sensor or even something with the solenoid block.
Let us know what you find out.
