Diesel Bombers - WTS light won't come on, alternator, tach won't work unless bump key

So I'm having a strange electical issue... I've got a recent problem that's somewhat predictable, but I haven't been able to narrow down the cause. The problem is that when I go to my truck, oftentimes the wait to start and other dash lights will not go on when the key is turned to the "on" position. The fuel pump (electric air dog) and radio and everything else will work, but nothing on the dash. When I crank the motor (usually takes several cranks) then the lights will come on and the alternator will work. If I crank the truck and it starts quickly, then the lights never come on and alternator doesn't charge and tach doesn't work. The first time I start my truck after sitting a while, it takes a few cranks so everything generally comes on, but after I shut it down and restart it, it starts almost instantly and the other things won't work. The WTS light, tach, and alternator all either work or don't, not separately. I can sometimes try to quickly bump the starter to make the WTS light come on so I know I can start the truck and have everything work, but sometimes no matter how many "bumps" i give it, I can't get it to work. Any ideas?? The truck is a 1996 dodge 2500 4x4. Thanks for any suggestions!