Manual Mode Issues?

[Pitter]

Driving down my mountain this morning I wanted to shift manual mode into 2nd for engine breaking but to my surprise I couldn't shift up or down in manual mode and no gear number appeared on the dash, just the small "m". Automatic with the shift lever moved to the right continued to work normally. When I got to the bottom I went to lunch and when I started the car afterwards "manual mode" was working normally. Any idea what gives?

 

[erhayes]

Manual mode won't shift into a gear that will cause over-reving the engine.