Thanks for all of the replies. I did pull the positive terminal on the 12v battery, and the Nav reset and reloaded as expected. I lost my radio presets, and my previous destinations. I did not lose my trip odometer, or my consumption history, or the nav presets.

Skywagon, Thanks for the mention of the 9v batter to "power port" preset keeper. On the TCH, the ports are switched, so it would be tough to keep radio presets. I'm not sure if this would also confuse the ECM computer. I'd hate for the car to try to startup without the battery for some reason, or for the car to try to charge the 12v battery from the traction battery. Also, I was trying to kill power to the Nav to force a software reload. I just wanted to know what I'd lose from the power loss.

Ray