Driving home a couple days ago I started getting a instrument cluster warning light and tone which I eventually determined to be the Differential Neutral Warning. I had no problem driving the rest of the way home. The light flashed continuously and the tone dinged continuously. Both stopped when I turned off the vehicle. Both started right up as soon as I turned the vehicle back on. When I turned off the vehicle I could not remove the key. I understand this also to be normal. I know to look for the sensor on the diff and attempt to adjust it. My first request of the Forum is any advice vis a vis finding the sensor and making adjustments to it. However, first, I need to know if what happened this morning was also normal. I attempted to re-start the vehicle and got nothing, as if the battery was completely dead. I still need to check the battery. I also found that I could now remove the key. Is the dead car part of the Differential Neutral Warning process or do I have two different problems? Any help the Forum can give me would be appreciated.