| Any electrical problems need to start with the fuse box.   LUV's have a weak link in the electrical system, the fusebox. The terminals the wires connect are riveted to the fuse holders. A little age and corrosion, and you get electrical intermittents. I solved mine by taking it apart and soldering the joints. Others have cleaned it with lemon juice, and others a new fuse box.  There is a fuse feeding the light switch and then another one for each of the 4 headlights.  It is quite possible for power to go into the fuse box, but not come out. 
 
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