I just tackled a grounding issue in mine. When I did my RMS, I removed the battery to frame ground and put it on the engine mount. This caused poor grounding because of the layer of paint and the amount of things the ground current had to travel through. So I chose a new spot and wire brushed all the paint off to make it shiny and bolted it back on. Works great now.
Thanks to JeepHammers write ups, I learned alot about electrical. If you go to this thread http://www.jeepforum.com/forum/f8/cj...trical-847238/
it will have other links going to Jeephammers writeups about making proper connections and grounding. He also mentioned the electrolysis disease where improper grounds can cause rust and corrosion. So there COULD be a possibility that buildup of corrosion has taken a toll on the wires. Best bet is to make some good grounds because you need good ones. Another practice i picked up was submerging the cable ends into baking soda+water to fight the corrosion. This helps fight up through the wire a little ways.