Land Rover Repair: Discovery I Running Lights Problem, fuse boxes, lighting problem

Question
Hi John, I was hoping you could help me with some problems keeping me from getting a mass state inspection on my 1997 Discovery I.  Basically I seem to have a lighting problem on the drivers side of the vehicle and the license plate lights.  When the headlights are on the side marker in the front doesn't come on, the running light in the rear doesn't come on (but the break light works in the same bulb) and the license plate lights will not come on.  To troubleshoot this I have replaced the bulb in the front side marker (it was blown), replaced the bulb in the rear tail light assembly (it was blown), replaced the bulb holder in the rear light assembly, replaced the lights/lenses for the license plate lights.  I'm having a difficult time figuring out where to try and trace this down next.  Any help would be greatly appreciated.

Answer
Sometimes problems like this stem from failures in the light switch.  Other times they come from corrosion in the wire harness, most often in the corners of the vehicle.  Finally, the fuse boxes on trucks like yours are problematic.

If you can't solve it we are in Springfield, MA

Good luck

John Elder Robison

Check out my car blog at http://robisonservice.com and find me on Facebook, too.  I'm @johnrobison on Twitter