One in a while, when I started my Jeep (99XJ, 110K miles, I6, auto, 4WD), the check gauge light will come on. When I checked the gauge, everything is normal except the battery gauge which is reading zero. At the same time, jeep seemed lose the power steering. But after 15-30 seconds, the
"check gauge" light will be off, the battery reading and power steering are also recovered?

What could be wrong? I just checked the battery connection, it is tight and no corrosion.