The generator light just came on in the DeVille tonight. I checked the voltage, and it's between 13 and 14 at idle, seems not bad. The FSM doesn't seem to have a very clear troubleshooting flow chart for this, and one of the main troubleshooting methods they talk about requires a special tool that's not available. I'd like to figure out what's wrong, if it's something that has failed, or maybe something like a VR out of adjustment, and then address the issue. If replacement parts are needed, I would definitely want to use an original style alternator and external voltage regulator. Anyone with experience on this system have any suggestions where to begin?