Chevrolet Repair: Power problem, ground circuits, lock cylinder

Question
I have a 1997 chevy 1/2 ton pu, 4x4, ext cab, auto trans, 350 eng.  A few weeks ago I was having trouble with the pu shifting.  It was throwing a kinds of trans codes, tach didn't work, no spedometer, no gear selector iluminated.  I took it into a near by mechanic, he said it was the ignition switch, which I had hime put it in.  It seemed to work, then a couple weeks later it did the same thing.  So I took it back to him, he called said it was fixed, he said his parts store sent him the wrong switch, so he installed the right one.  I brought it home but the radio didn't turn off, I didn't think much about it untill a couple days I went to use the pu and the battery was dead.  I charged the battery, clock stays on and the radio will play if you turn it on.  I asked the mechanic why it was doing this said he thought it was the lock cylinder because it was loose, so I ordered one and put it in the pu, still the same thing.  My question is it a broken wire or a faulty switch, or didn't the mechanic get the ing switch installed correctly?  Thanks!

Answer
Hi Alan,
I would be looking at ground circuits.  Make sure that all the grounds are clean and tight.  And look at the main bulkhead coming in from the firewall into the dash and make sure that the area is clean, and no corrosion.  I wish I could help further but unfortunately it's kind of vague.