Voltage regulators can cause unusual problems. Right after I installed an HID headlight system this summer, I started having an intermittent issue where the LCD odometer would flicker, the check engine light on the speedometer would come on and the HID headlight would go out. The engine would not skip a beat, it would just putt on down the road. This would happen at any time, but usually not when it was cold but after it was warmed up. When it was warmed up, it would happen right after starting or while riding down the road. Sometimes it would not happen for several long rides. It only lasted a few seconds so I could not get a meter on it in time so I could never find anything wrong.

It started happening more frequently and finally it failed right after I cranked it up one morning and I was able to get my trusty Fluke multimeter on it just in time to see the battery terminal voltage going through 17 volts before it suddenly jumped back to 14 volts and everything was good. I was able to see it happen again a couple of times so I put a new voltage regulator on it and the problem has not happened again since.