Electrical System Flunked

Electrical and Ignition

  1. Mason Moran

    Mason Moran Well-Known Member

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    Hey all. I just got my first project car!! A 1974 Duster with a 225 and automatic transmission. One of the things that need fixing in this baby is the electrical system. I was told that the headlights some times work (though i haven't tested them yet). The blinkers never worked with me and I presume the brake lights are also duds. The car has a separate button that needs to be pressed while the key is turned to start it. Also the battery drains if left plugged in. What is the best route here? A new harness? And how do I get it to start with just the key?
     
  2. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    Hard to say, especially without photos. "It might be" that all of that could be fixed, but if the wireing is a victim of hacks, smoked, melted, and corrosion, then yeh, rewire. If you can't fix what is there then it might be a big job for you to tackle

    So far as the separate push button, the annoying 74 only U.S. Federal "safety" "seat belt interlock" might be to blame.

    So start right there. Look for the reset button under the hood on the driver's fender panel. There should be two "yellowish" wires. Splice them permanently together.

    100_0894-jpg-jpg.jpg

    You need to scare up a factory shop manual, and unfortunately, MyMopar which has free downloads of many of them, only has up through 73, which has a number of differences
     
  3. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    So far as a drain, start with a test lamp. Disconnect the battery NEG and insert the test lamp in series. If it lights brightly, and is a small lamp, try a larger one, such as a stop/ tail lamp bulb. Disconnect things one at a time to find. Pull fuses. Check the glove box/ courtesy/ trunk lamps.

    Look for aftermarket "hacks" especially stereo amplifiers, etc. Disconnect the big black wire going to the alternator and see if that kills the drain. BE CAREFUL as that wire is not fused, and is a main wire, will burn smoke and melt!!! If shorted!!!
     
  4. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    lights. Get yourself a multimeter, a 12V test lamp and some alligator clip leads. Check up front around the rad support for the headlight grounding wire, bolted somewhere onto the body possibly near the battery. Make sure it s clean and tight. Pull the headlights. "Work" the connectors in and out several times to 'scrub" them. Check the bulkhead connector.

    "The path" for headlights is:

    Coming off the ammeter black main wire up under the dash is a big factory "welded splice" This feeds off to several components.......the ignition switch, the fuse panel "hot" buss, and power to ONLY the headlights (not tail or park)

    That headlights power to the headlight switch should be checked pull out the switch so you can access it.

    Before you do that, however, the power comes off the light switch TO the dimmer switch on the high or low beam wires, which pass through the bulkhead connector. Those two components are trouble spots. "Wiggle test" the dimmer switch and connector. Go around into the engine bay and 'wiggle test" the bulkhead connector.

    There has been "books" written on troubles with the bulkhead connector. Learn to pull the sections apart, inspect, and repair. The ammeter circuit is a BIG issue.
     
  5. halifaxhops

    halifaxhops It's going to get stupid around here! FABO Gold Member

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    Electrical issues can be a real PIA. As stated above get a good FSM with the correct wiring schematic. Test light, ohm meter and I love a current indicator old school shows which way the drain is coming from, to get you started. You do need to understand how voltage flows also. Think of it as water through pipes.

    s-l1600.jpg
     
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    • Mike69cuda

      Mike69cuda 64 is the new 17 FABO Gold Member

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      If I had it to do over again I would by all the harnesses from Year One and do them all at once rather than chase electrical gremlins forever.
       
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      • fklskv

        fklskv Well-Known Member

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        Are the wires all hacked up? This forum loves pictures.
         
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

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        Not much to add here but maybe a couple things will help.
        The brakes lights are on a seperate circuit than the turn signals. Brake lights get power whether or not the key is turned on. Turn signal is powered from the accessory feed - which requres key in run or accessory.
        "Accessory" is anything not critical to running the engine.
        Hazzards were powered different ways in different years. Regardless, the switch gets power at all times including with key off.

        A meter like Halifaxhops posted indicates current flowing in or out of the battery.
        It is not sensitive enough to show very small drains, but if it shows discharge with the key off, that's a clue where to start tracking down the problem.
        If it shows discharge with the engine running, then that indicates the alternator is not providing enough power to recharge the battery. It should show charging after startup, and once that is done should show no current flow.
        Current to added electric devices between the battery and the meter will not show as discharge on the meter. As 67Dart273 wrote, you must check that.
         
      • BWDart

        BWDart FABO Gold Member FABO Gold Member

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        I bought a big 11x17 laminated wire diagram from classic car wiring you might want to get one the others I downloaded weren't all that good
         
      • halifaxhops

        halifaxhops It's going to get stupid around here! FABO Gold Member

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        My 74 was hard to find a diagram that was right, had three to make one. Turns out the later built ones used the volare diagram, WTF?
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        Do you know where to download a Volare diagram? I sure don't.....................
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        "Something picks" at my brain? I know I did a really poor scan of a 74 paper manual electrics and it might be posted, maybe on TB's site?

        Maybe the 76 manual.............
        Not tremendous quality, but I scanned the complete 76 A body wiring diagrams from a paper manual. Give a "Thanks" to TrailBeast who provided a host

        www.letsgocomputers.com/docs/76wiringAbody.pdf

        In the back are outtakes for the AC stuff and heater
         
      • cudamark

        cudamark FABO Gold Member FABO Gold Member

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        Basically, without know more about your car, or, any photos to go by, if the wiring isn't hacked up or major mods made, I'd trouble shoot it an repair as necessary. If it's been modified too much, I'd replace the harness. In my experience, that year seems to be the most trouble prone of all the A-bodies.
         
      • halifaxhops

        halifaxhops It's going to get stupid around here! FABO Gold Member

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        I have to look I might still have it. Some one gave me it.
         
      • Mason Moran

        Mason Moran Well-Known Member

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        I've posted before and now I've got pictures. Not sure what is going on but next to nothing electrical works. No lights to my knowledge, some lights in the instrument cluster work, and the battery drains if left plugged up. Any help would be great

        PXL_20201004_212725785.jpg

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        PXL_20201004_200146188.jpg

        PXL_20201004_200139534.jpg

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        PXL_20201004_200125425.jpg

        PXL_20201004_200119930.jpg
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        WHAT ARE we workin on? Year/ make model? 73? 74?

        This is gonna be difficult or impossible to troubleshoot by remote control, because that wiring is one hell of a mess and all hacked up, obviously. Please post a link to your old thread.

        Start with the horrid battery terminals. The path for power into the car to run basic stuff like headlights, dome light and ignition switch is:

        battery...............starter relay 'big stud'............fuse link...........through the bulkhead connector on the big RED wire...........to the ammeter.........through the ammeter and out on the big BLACK wire.........to the under-dash welded splice..........and branch off to the alternator, the ignition switch, the headlight switch, and the fuse panel "hot" buss

        READ the MAD article as it covers primary power distro

        Catalog

        ...........and that article contains a nice simplified diagram of primary power. You would do well to learn and memorize that diagram

        NOTICE!!! that other than the fuse link---which is darn poor protection---NONE OF THIS part of the harness is FUSED!!!! (You can burn stuff down!!)

        amp-ga18.jpg

        Go to MyMopar and download yourself a service manual and then download the 3rd party wiring diagrams from that site, as well
         
      • Mason Moran

        Mason Moran Well-Known Member

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        Sorry this is a 74 Duster 225 automatic. Should have included that immediately
         
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

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        How about we ask a moderator to combine your threads. @toolmanmike can you add this to the previous?


        We can see from your photos a serious amount of jerry rigged wiring.
        One possible issue is the '74 interlock that was mentioned.
        But there is a lot more going on that will need to be addressed ergardless of whether the interlock is working.

        What is your goal with this car?
        Do you want to restore it? Just make drivable?
         
        Last edited: Oct 4, 2020
      • Mason Moran

        Mason Moran Well-Known Member

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        My goal with this car is to have it be a worry free fun machine pretty much. Not looking to put restoration quality work into it. This is my first project, and I just want to have something fun to drive around in. I want everything to work, but the world won't end if I put parts on it that aren't original.
         
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

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        In my opinion you have two choices with some options within each.
        1. Get a decent engine harness from another '74. Check it over, Swap it out.
        2. Rehab the existing wire harness. This will be a project. In part puzzle, part learning experience.
         
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

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        Here's what I see.
        upload_2020-10-4_22-53-8.png

        The big cable to the starter is only important for starting. It does nothing else.
        One of the red wires with a ? should lead to the starter relay. That's the original main battery feed. Find it.
        upload_2020-10-4_22-59-7.png
        Connected to the same stud on the starter relay should be another wire. Remove the wrapping if any, and follow it.
        It also was red but will have a short blue wire (fusible link) somewhere in it. It should lead to the firewall. Probably to the multi-connector.
        Since there are extra red wires on the battery clamp, you might want to follow them to see where they go. It all depends on whether you care to figure out what was hacked or just want to put it back the way it should be.

        On the alternator, it looks like the original output wire is still in place but there is a red wire added.
        upload_2020-10-4_23-7-32.png

        The heavy black output wire should go to the firewall. In the diagram its marked R6 (R for alternator).
        Remember this is all hooked to the battery so will be hot when the battery cables are reconnected.

        That should get you started on tracing what should be there and where it goes.
        They should connect on the inside with the power feeds to the key switch, hot side of the fuse box and headlight switch.
        When the engine is running power comes from the alternator. When the engine is starting or alternator can't provide, power comes from the battery. Pretty simple.
         
        Last edited: Oct 4, 2020
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        ^^The other thing I darn near mentioned^^ is the OP ought to seriously consider finding "an old local guy" who is willing to lead him a bit, "for a few bucks." Somebody like me LOLOL. Even if it's some knowledgable old guy who can't crawl around etc anymore, he could step you through some stuff, you could take notes, and then dig in and fix it "in between" visits. Maybe put an ad on C/L or fakebook

        How big is your town/ community, or how far from one are you?
         
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        • toolmanmike

          toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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          I just read this and will work on it tomorrow.
           
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          • Mattax

            Mattax Just the facts, ma'am FABO Gold Member

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            Good advice!!!

            By the fire wall grommet we see a fusible link.
            upload_2020-10-4_23-19-50.png

            If its connected to the wire going through the grommet, then this car may have one of the heavy duty wiring options.
            So take a closer look at that grommet wires and that link. Tell us what you see, take a pic, or both.
             
          • toolmanmike

            toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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            I think I got it. Tough on a cellphone sometimes
             
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