Wiring problem - needle in a haystack

Wiring problem. 89 Caprice station wagon - automatic - 307 engine
For the last few days I have had a problem. Sometimes I turn on the headlights and they dont work. Othertimes they are fine. But it's
not just the headlights. The dome light, horn, clock, radio, power windows, and other stuff dont work. Yet, the engine starts and runs fine. The brake lights also work as well as the red lights on the dash when I start the car, but not the lights that light up the dash.
I thought I may have had a bad ground. I removed the ground wire from the body (goes to the battery), and cleaned it. I also cleaned the battery terminals. That did not solve it.
I have had a starting problem going on for several months, whereas the starter did not engage in the flywheel every once and awhile. I decided that maybe the solenoid was not only the starting problem, but possibly the reason for this "lights out" problem. I got a new starter and replaced it. I cleaned all the wire terminals that go on the starter before replacing them, and made sure the ends were not loose on the wires. After replacing the starter the lights worked fine, so I thought I solved the problem. Last evening I stopped in town, and when I started the car, there were no lights again. While the car was sitting, the dome light, clock, etc. all came back on by themselves. As soon as I flipped on the headlight switch, the dome light, clock etc. went dead again.
I have confirmed that the ground is good to the car body, because to get the car home (at night), I knew I had to somehow get headlights or face the police, so I spliced a wire from the headlights supply wire, directly to the battery. (just the hot lead). The lights worked fine. While driving home, suddenly all the things in the car started to work again (horn, dash lights, clock, radio, etc).
This really has me puzzled......... What the heck could be causing this? I downloaded a wiring diagram from autozone. It shows several fusible links. But WHERE ARE THEY LOCATED? Are they inside the harness? I sort of thought that if a fusible link burns out, that's it. Unless somehow one of them is barely touching internally. It;s bad enough trying to trace something like this, but whenever I start to trace it, the power comes back on again. Talk about frustrating....
Anyone have a clue where those fusible links are?
*** One other thing. There is a steel line that is connected to a vacuum line on the top of the engine, drivers side / rear of engine. It's not connected to anything under the car. I saw it when replacing the starter. It ends right near the exhaust pipe heat valve (that thing that flips right under the ex-manifold. Does anyone have any idea what this line is for? It's about a 3/16 dia. steel line with a pointed end (below).
Thanks
George
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snipped-for-privacy@nospam.com wrote in

fusible links are right there at the solenoid, small wires hooked to the positive stud with battery cable.......that was my first thought after reading first paragraph........they do break internally with no visible evidence at times........kjun
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wrote:

Thanks for the reply. The question now is how do I replace them?
George
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snipped-for-privacy@nospam.com wrote in

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you can either buy a fusible link and solder it in or buy a roll of fusible link wire on a spool. ive replaced so many thru the years (burn jobs mostly) i use a spool.......insure that is the problem by wiggling suspected wires and see if circuits are affected before bothering on a guess tho......................kjun btw: steel line mentioned sounds like GMs original vac. supply for heat riser
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wrote:

Thanks for the reply. I jiggled every bit of wiring harness, banged on the fuse block and pretty much beat the crap out of the wiring and I can not get the lights or other stuff to go dead again. This is worse than if it just died completely, because I know it will happen again, and it could be at the worst time. Maybe I should just replace all of the fusible links because I dont know what else to do. In the meantime I have a bare spot on the headlight feed wire and am carrying around a short wire with alligator clips on the ends. At least that way I can jumper the lights directly to the battery. Intermittent problems are the worst. The lights have worked for 2 nights now ????
OK on that steel tube. Yes, it ends right next to the heat riser, but I dont see any hole to put it. Is it even needed? If not, should I plug the tube (is it a vacuum leak)? I have always had a bad idle with this car. It runs fine, just idles crappy. I can not find any other vacuum leaks and did everything to the carb I could. Seems the hotter the engine gets, the worse the idle. I've just learned to live with the idle issue, but maybe that steel tube is the culprit.
Thanks George
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snipped-for-privacy@nospam.com wrote in

remember george, im not saying it is a link failure. im simply telling you where they are!.....for diagnostics I would 1) unhook all links 2) hook them up one at a time to figure out which link FOR SURE controlled the circuits involved. 3) if a common link suppies all circuits that fail start backprobing until open circuit is found. intermittants are a bitch and you will probably have to do all tests while system is faulted......also, when system fails hook a jumper cable up between battery ground and clean frame point to insure ground path.........heat riser prob?? = make sure riser is open and wire it to stay that way. i imagine it is open or you would have driveability probs and overheating. plug all vacuum leaks..................kjun
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Using this clue I'd say the battery cables need to be checked/replaced. Don't rely on how good they look. Check the resistance on each cable.
Dave S(Texas)
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On Fri, 07 Jul 2006 02:15:51 -0500, snipped-for-privacy@nospam.com wrote:

Undo the bulkhead connector (the big taped up wire bundle) at the fire wall and inspect ALL the spade pins for burn marks. Particularly on any of the larger wires. Sounds like the problem is there. GM uses the same size pins for all wire sizes and current loads and these are udersized. Not a new situation.
If your any good at soldering, run a bypass wire(s) around the burned one(s) and solder it in place . Do not use spade or crimp connectors. Make sure the new wire(s) are protected from the firewall metal.
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