1981 D150, when I turn the head lights on, the temp, oil pressure and fuel gauge slowly drop. The door buzzer turns on and the turn signals on the dash light. Anyone ever seen something like this?

Probably your dashboard has lost one or more of its grounds, so when you turn on the headlamps, the instrument cluster lights ground via random paths, causing random electrical behaviour like this what you describe.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Well, I did find a post on the instrument cluster marked ground with no wire connected so I added one and nothing changed. I checked voltage at battery and moved the ground to motor, frame and body and all read the within a few hundredths of a volt. I found a broken ground from the box to the body and fixed that and no improvements.

I hate when I get frustrated but I sure am at a loss right now.

You will need to follow the wiring harness under the dash and look for the grounds that branch out from the main loom. Clean and tighten these connections.

I found the problem. The connector on the (back) right side of the instrument cluster for the fuel and oil pressure gauge, it connects to a bunch of pins on the instrument cluster circuitboard itself. Those pins broke off the board and we're stuck inside the connector not making any contact to supply signal. I took the instrument cluster out and soldered the pins back on to the circuitboard and it worked perfectly. I could have done a little neater job if I cleaned or replaced my soldering tip but it did fix all my problems. The symptoms of this broken pin issue was oil pressure and fuel gauge not working. Also the highbeam indicator was on sometimes when the highbeams weren't on, like it was in reverse. Sometimes both turn signals would be on but not flashing. It was random electrical glitches and many functions of the instrument panel.

https://youtu.be/efWReUzWFvw

I've disconnected and reconnected and feared every time of this from destroying her, as this plug on the A-bodies, from the mass majority of things I have fixed, does appear to be the most fragile thing on the automobile...; I've heard about these pins breaking and the boards not being replaceable, which isn't a problem, with a little solder.

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exoJjL

When I get around to cleaning up the wiring on my 76 D100 truck I am going to splice in a modern plug in the wiring that goes to the plug on the back of the circuit board on the instrument cluster. That way I can leave the factory plug installed on the delicate pins and just disconnect the modern plug farther up the wiring harness. Radio Shack sells such plugs.

FEMALE END

MALE END

My 67 Dart suffered from disconnected pins from circuit board. The fix was to make up a sub harness solder each lead to its respective copper ribbon where pin once was connected, and mate this harness to existing harness with a new male & female multi connector six to ten inches from circuit board. This method eliminated any strain that would be present if one were to reattach pins to ribbons on board reusing old pin connector, and afforded easy disconnect when needed.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC