Strange electrical problems in my 2003 GMC Sierra 2500 crew cab. First thing that happened several months ago was the rear power door locks quit working - front work fine. A few months later, the rear speakers in the door quit working - front speakers worked fine. I figured it was something isolated with the rear doors. Next, the front drivers side speaker quit working randomely. It usually plays at a very minimal audible level (very low) and does not cut out completely - but randomly will work flawlessly. The next thing to go whacky is the "chime" for the headlights or key left in the ignition, etc. It will work sometimes, but usually does not. I think that when the chime works, the drivers door speaker works - but can't say for certain. Rear door locks and speakers don't work at all - not even randomly. I'm not a mechanic, but am hopeful that someone might have an idea of what I can check so I might save myself a huge repair bill. Thank you!