This past Monday night while I was driving my 83 GMC JIMMY (full size) in the rain, things started to act weird. The first thing I noticed was that my windshield wipers were switched to intermittent, and they seemed to be swiping across unusually fast. Second, when I turned on my blinkers, they were also unusually bright and flashing a little fast, it was the same story with my windows. The passenger side, usually goes dwn/up pretty slow, but that night the window was zipping up and down as if the motor was brand new. It had seemed as if the whole electrical system was somehow being excessively overcharged. There was no smells of electrical wires burning in the cabin or under the hood, no smoke. I drove it home, the next morning I had no power to anything except hi/low beams, cabin lights and parking lights.
My initial theory was that the voltage regulator in the alternator went bad and was overcharging the system and fried the ignition switch. However, the battery didn't fry and the alternator passed a standalone bench test yesterday @ AutoZone. The only test's I've done so far was verify 12.4 volts at the battery terminals and 12.4 volts at the alternator, prior to bench testing. If anyone has had these issues or can give me some "did you check this" or "try this" suggestions, it would be greatly appreciated. In the meantime, I will be starting a full combing of point to point continuity checks working from the battery to the cab.

 

Too bad you didn't check the alternator charging voltage while it was running. Sounds like it was way overcharging the system. You could have burnt out a bunch of different things.

 

Ok, so yesterday after work I was able to begin my dreaded point to point diagnosis of my faulty electrical system. I also took a few pictures and attached a schematic I marked up of where I was able to verify voltage and where voltage is absent, but should be present. The first attachment for this is "1983_wiring diagram-CK trucks.pdf". The second shows a view of the motor and the circled area of one of my electrical connection checks "Engine bay_power link bar". The third is a close up of the power link bar "Engine bay_power link bar wire description". The fourth is a rear view of the power link bar "Engine bay_power bar_rear_view". Last is a burned wire (yellow) coming from the right side of the power link bar. Again, any help/suggestions are appreciated.

*Combining Consecutive Posts*

Ok, I did attach the four files, but I guess it only allows one attachment at a time. How should I post the other three files that are described in my post above?

 

I am not sure if you can attach files (pdf's, txt, etc) at the same time as images... For images, it is just easier to use photobucket, imageshack, picasa, etc. If you wanted to keep it on the forum, you could upload them to your gallery and then link to them in your post.

 

Thanks' swartlkk. I've never really been all that engaged in the forum board world until now. I'll try your suggestions and thanks for acknowledging my posts. If I end up changing out the ignition switch this weekend I'll document it and post it. Outside of this forum, I really didn't find anything that captured the process.

 

No problem! There aren't anywhere near the number of fullsize guys/gals on the site as there are s-series, but we'll try our best to help solve your problem!

 

Well this past weekend I took on foregoing and dreaded task of doing a full point to point diagnostic check on my electrical system. I rechecked my previous verification to make sure nothing changed where I found 12.4 volts and begun working my way to the firewall. One of the things I first noticed was that the schematic from my Chilton book, didn’t exactly match what I was physically looking at, which gave some confusion. For example, there were more connections in certain areas than what the schematic showed. After approximately three hours into the job, I finally traced and found the “fusible link”, which was burnt at both ends. I noticed this electrical break in the system the following day after the “paranormal activity” began, but I didn’t give it much attention, because I didn’t think that one "small" wire could have that much influence on the system as a whole. Well after a quick trip to AutoZone for a replacement fusible link, some quick solder work, I turned the ignition switch to on and Jimmy was freed from the hex. I will post a picture soon of the new fusible link and where it is located. Thanks for all the help.