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Electrical systems flicker


Datnis5

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Hey guys, I have a somewhat starnge issue today coming home from work in the 710. It was raining and as I approched a stop sign I noticed my Charge light illuminated for a brief sec. then as I went to accelerate again, the Charge light went out, my dash lights came back brighter (hadnt noticed they dimmed as it was in afternoon), I could smell a brief burned electrical smell but did not see any smoke and checked wires and fuse block when I got home nothing burned or melted. Well now when I start the car, the door buzzer is chiming rapidly and increases with engine rpm, and whenever i hit brakes/turn on headlights everything flickers. radio dome light dash lights. and after the intial happening of it my radio had reset all presets like the battery was unhooked. All connections are tight look in good condition, pulled chassis ground cleaned it. I dont know where to go from here, any help is greatly appreciated. car is a 74' 710 2 door sedan w/L18 automatic. and it has set for a little over 6 months, and has a new battery.

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Ok I checked all my connection plugs, and cleand ground again and replaced negative batt. cable. Car is still doing same thing. And this morning I noticed w/ headlights on the wires coming from the headlight switch get pretty hot and if i hold the brake pedal down said wires get even hotter as do the wires coming from the brake light switch. Could it be an overcharging altinator or bad voltage reg.? I didnt see anything that could be shorting out or any melted wires/plugs. And also now with key in off pos. I have no dome light/door chime/or park lights. Headlights are all that will come on without car running.

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Easy to tell if it is overcharging: Put the voltmeter on the battery. If it's over 15 volts it's overcharging. But most likely there is still a loose connection somewhere, like under the dash. Hopefully you don't have any wires twisted together by hand.

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I believe you have several problems that are unrelated, other than the fact that is is wiring issues.

 

Charge light flickering, and the dash lights getting bright after revving the engine. This happens to me with my 521, when the brushes were worn out on the alternator. This was with external regulated alternator. The alternator unregulated would just put out more and more voltage as the engine speed is increased. The voltage regulator applied full battery voltage to the coil inside the alternator that controls output, at low speeds, and as the engine speeds up it starts to switch the coil on and off. If the brushes are worn out, they do the switching at all speeds, and the alternator only puts out enough voltage at higher engine speeds.

 

Your headlight switch and wires should not be getting hot. If it is, it has poor contact inside it, or it is overloaded, and will soon fail completely. The parking lights should have a separate fuse, and an independent section of the light switch. A previous owner may have rewired the parking lights, or the brake lights, into the headlight circuit. On most cars, the brake lights are also a separate circuit, independent of either the headlights or the park lights. Your headlight switch may be getting hot because it is overloaded with other electrical circuits

 

After 36 years, all the electrical connections could be bad. All of them. There probably are connectors between the engine room wiring harness, and the dash wiring harness, and possibly a body wiring harness. Any of these connections could get some corrosion in them after 36 years, and need to be cleaned, or at least taken apart, and put back together to make good contact again.

 

You need to get an electrical wiring diagram for your car. You need to confirm that the previous owner did not just take an electrical circuit that was not working, and just jump it to one that worked, when it quit working, so all the circuits are running off one fuse.

 

Because of a poor mounting location, 521 guys have been dealing with fuse box issues for years. The 710 probably has a much better location for the fuse box, but again, it is 36 years old, and could have issues with the fuse box.

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Alright guys I got my problem figured out, ggzilla I did have a loose connection in the way of a wire someone has previously re-engineered that was disentigrating inside the insulation, looked to be too small of guage wiring. And also I did have a bad alternator as you said I probably had multiple issues DanielC, so thank you guys for helping me out, and when I get some free time I am going to fix the wiring were it was screwed up the proper way.

 

 

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Oh and by the way for anyone that might have or run into a similar issue, the wire that was screwed up was the wire that feeds from the batt. to the three fusible link wires that go into the relays, as said above it looks like they used too small of wire and the copper conducter part of it basically just fell into pieces.

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This picture shows the fusebox, barely. look at the top right edge of the picture, and there is a black thing, that has a red wire, with a yellow terminal end on it. That black thing is the fuse box.

BatteryTray1.jpg

This is another picture of the engine compartment. The fuse box is in the far corner of the engine bay, right below the hood hinge bracket.

EngineOut2.jpg

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