Okay, my 1986 GMC Jimmy (6.2L diesel) is having an odd intermittent problem: when I put the key in the ignition and turn it just short of activating the starter (as I have to do in order for the glow plugs to warm up), nothing that should activate at that point (glow plugs, heater, blinkers, wipers, radio) work. If I continue to turn the key, I get no starter. The truck is dead, but all of the items directly linked to the battery-headlights, interior lights, brake lights--and are at full power. Just none of the items that require the key to work will activate. The first time this happened, I towed the Jimmy to the shop and the first time they tried to start it, it worked like normal. I thought it must be a bad ignition switch, so I had it replaced. Fixed, right? Wrong. About a week later, my son borrowed the Jimmy and went to a friend's house. When he went to leave, the same thing happened--none of the ignition items worked. He left the key turned to the "on" position while he called to ask for advice. As we were talking, everything came back on and he drove home. I took it back to the shop, and they replaced battery cables throughout. Today, about three days after the repairs, it happened to me again. I went into a store, came out, and no power when the key was turned on. Again, lights, interior light, etc. (all those things directly tied to the battery) worked fine and at full power. I left the key in the ignition and turned on and I waited. Ten minutes later, it all came back on. Of course this never happens when it's in the shop, which makes it very difficult to diagnose. I'm at a loss, but it seems like it has to be one of two things: (1) either I got a faulty ignition switch when I had it replaced, or (2) there is a short in the ignition wiring itself somewhere. Anybody else have any ideas as to what might cause this? It's driving me crazy; I can't take the thing anywhere because I never know when it's going to work or not work.