I am currently deployed and my trusty 2001, 4.3L, 4WD may have let me down for the first time.

The battery died recently, which the wife replaced with the help of a friend. On her first drive after replacing the battery, all cluster lights, headlights (DRL, LB and HB), radio and rear view mirror lights went out. The parking lights function if she turns them on manually, and if she manually turn the head lights on, they flicker occasionally and randomly. If she attempts to turn the brights on, all cluster indicator lights illuminate and the gauges fluctuate as she holds the switch back. As soon as she releases it, they all remain without power. After changing the battery, everything functioned as normal. She drove it to her destination, did her business, and began driving home. During the drive home, everything went out.

What gives?