I have a 1990 cherokee laredo (V6, automatic) I got about 3 or so weeks ago. It was 550 bucks, so I couldnt pass it up, I've encountered a few problems that I could use some advice on. I'm not exactly an auto expert but I can find my way around. I got a whole bunch of questions, I'm not looking for someone to answer them all but if anyone knows an answer or two to them I'd greatly appreciate the help.

First off, I have all sorts of problems getting it to shift out of part time. I've tried to get it to go into 4x4 or front wheel while in drive, park, neutral, at high speeds, at low speeds, off road but it won't go. After a while I'll just leave it in full time and after a while it'll shift over. Think my transfer case is crapping out or it's just a bolt or cable?

Next, the rear wiper seems dead, but is there any way I can determine if it's a bad wire/dead wiper motor/dead switch? The rear washer still shoots fluid, but thats it.

Also, it just had a new alternator put in but I think the voltage regulator might be in bad shape. At night when I have the lights and such on my battery gauge is showing about ten volts or lower when I'm not moving. Once I get moving or if I put it in park and give it gas the lights get nice and bright and the gauge will get up to a nice 13.8 or so. But once I'm at a stoplight the gauge is dropping and the lights are getting dim. Voltage regulator, a short somewhere, or something else?

Thanks for taking the time to read, any guesses would be greatly appreciated.