electrical issues, dimming lights, occasional stalling, rough idle at stop

Electrical & Ignition

  1. Evan Frucht

    Evan Frucht Well-Known Member

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    What alternator did you get that was 80 amps? What alternator options do I have OTHER THAN what the part stores say will fit.
     
  2. Evan Frucht

    Evan Frucht Well-Known Member

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    Also how can I test the voltage regulator on my instrument cluster. I've bought a few used clusters for parts so I have spares but I'm not sure if any of them actually work properly? Could this be part of my problem. My temp gauge seems to work normally as it should, my gas gauge works sometimes... when it does it seems accurate. Other than that everything acts normal. The dash clock works, I converted it to quartz.
     
  3. RJRENTON

    RJRENTON FBBO Gold Member FBBO Gold Member

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    IMO....
    Do your own due diligence re alternators. Its highly probable that the parts store counter person has a very limited knowledge of alternators how they work and what you need other than year, model and engine. POWER MASTER's are reputed to have high output (amperage) ratings that will fit and function as a OEM Mopar unit. They even resemble a square back alternator if appearance is important aspect to you. They are available in chrome, single and double sheave construction. If changing yo a high amperage unit, pay attention to the wiring, especially the bulk head connections snd the fusable link connection. There a few threads on this forum that detail the advantages of up grading the wiring. Just my opinion of course.
    BOB RENTON
     
  4. Moparnocar

    Moparnocar Well-Known Member

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    It makes 5 volts by using a bimetal strip, that heats, up and breaks contact continually. Dropping 12v to 5v

    You could hook up a old style needle multimeter, and look for a fairly steady swing 5v to 12v

    Otherwise, just look for 5v on the gauge power wire

    Or get crazy, hook up scope, and watch the swing waveform, that might be Overkill tho..
     
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    • RJRENTON

      RJRENTON FBBO Gold Member FBBO Gold Member

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      OR....consider just replacing the old bi-metal OEM MOPAR unit with RT Engineering's electronic unit that has built-in protection against short circuit. Its a direct plug in replacement no wiring mods required. I have one on my origional RS23V0A****** GTX. it provides 5 volts to the gauges so they operate with reasonable accuracy and repeatability. Just my opinion of course.
      BOB RENTON
       
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      • miller

        miller Well-Known Member

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        First, I'd strongly suggest one of the RT Engineering units. I went through my panel, with a spare, choosing the parts I wanted to use. But...I screwed up! I had the old voltage reducers, but decided to get a new one. It only lasted a week, before going out, and cooked my fuel/temp gauge. So, yeah, had to have the gauge rebuilt, and got the RTE reducer unit. All good to go, now.

        Alternator? Not that it matters, but my 64 sports a 69 440. Only saying, I had parts and pieces laying around, that I could choose from. I picked the best alternator I had, and had it tested and rebuilt. That's when I was told it was an 80 amp...was hoping for a 60 amp. After research, and being told it wouldn't hurt, it got slapped on. I'll note here though, especially since I was adding more amps, I added parallel wiring to the alternator. Yeah, that's something you can look up. Adding that wire, that went straight through the firewall, with the 'stock' wires going through the block, split the amp load. And, it's hooked up to the stock ammeter, too. Works great!

        Though...a big but here! 45 amp, or 80 amp, still the same deal. MUST have good wiring/connections, and the other devices in that charging system. Okay.

        I went through every inch of wires, in the entire car. Most of the electrical components should/need to be checked. If any wire had more than 0.5 ohms reading, it was replaced. So on, and on. If the wiring isn't good enough, it only makes problems.
        IF the wires are good, corroded connectors can be cleaned with...lemon juice. I used a container, that the ends of the harness could fit it. Let it soak for a day, rinse with water, and their clean.

        Is it all a job, yeah.
         
      • miller

        miller Well-Known Member

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        You know...something you might consider doing, and might correct some things.

        Quite a bit of this electrical stuff, can get into high $$s. Have you had the alternator tested? Personally, I wouldn't trust any electrical part from a parts house. Much of it is junk. If your alternator is good, okay, or find an alternator/starter rebuild shop, and let them fix it. You can also ask if they can change it, to a 60 amp, which would be fine.

        Voltage regulator, on the firewall, can be checked, and if an original, can be cleaned up, adjusted, and re-used.

        Assuming your under the dash wiring harness is 'okay', I'd suggest you pull both under the hood harnesses. One is charging/ignition, one is for headlights. Then, under the dash, loosen the dash harness 'block' from the firewall. With that loose, stick it in some lemon juice, so any corrosion in the block/contacts can get clean.
        The two under the hood harnesses...check each for condition, ohm check each wire end to end, and replace any bad wires.

        Just dealing with the wiring under the hood, might fix some of what's going on.
         
      • Evan Frucht

        Evan Frucht Well-Known Member

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        I'm not sure if I'm doing it it right to check for voltage drop becuase I'm getting fluctuating readings on my new digital mutimeter.
        When I check from my battery negative post to body I get a reading of -2.6mv. When I test between battery positive and alternator positive I get a -0.9v reading. Yes first one gave me a MiliVolt and second one is Volt.
         
      • Moparnocar

        Moparnocar Well-Known Member

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        Is this with the car running,? Meter set on 12v-20v scale dc?

        No idea why the milivolt reading. If it is TRULY .9v drop from battery to alt, id consider that high, clean connections, ohm out wire when off to confirm its corroded/broken iternally
         
      • Evan Frucht

        Evan Frucht Well-Known Member

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        The new multimeter I got off amazon was advertised as being AUTORANGING. Didnt really know what that meant until now. I guess that's why its giving me the milivolt reading, assuming that my battery to body ground is good.

        I think the .9 volt drop is accurate.

        Also, I brought my car to a local old time alternator shop today that's been around forever I think. A one man operation kind of deal. He took a brief look at the cars ammeter while running and listened to the symptoms. He said it seemed to be charging but to take it off the car and bring it back to him... he said "I'm curious about something" ... and that "sometimes the diodes start to go bad and that can cause issues"

        So I may do that just for the hell of it and see what he says. Maybe it's part of my problem. Atleast if I have it rebuilt I'll know for my records that it was done properly.
         
        Last edited: Dec 2, 2019 at 10:16 PM
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        • khryslerkid

          khryslerkid FBBO Gold Member FBBO Gold Member

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          The square back is what I'm thinking you have and the diodes are easy to see. If just one of the six are burnt it will act up.
          Screenshot_20191202-234053.jpg

          The round back can burn diodes but they don't always show that they're bad. Either alternator is an easy fix.
          Screenshot_20191202-234027.jpg
          Sounds like the guy you found is the right choice. Not too many of those shops around anymore.
           
        • Evan Frucht

          Evan Frucht Well-Known Member

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          I have a round back one
           
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          • miller

            miller Well-Known Member

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            Same thing I have, Evan.
            The shop that went through mine, and told me it was an 80 amp, also mentioned it could pretty much be changed to any amp I wanted. You might ask your man about that. Don't ask me! Sometimes, I don't know which wire end is which! :p
             
          • RJRENTON

            RJRENTON FBBO Gold Member FBBO Gold Member

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            FYI...
            The capacity (output amperage) is detetmined by the stator windings and the amperage ratings of the diodes. EITHER the round back alternator or the square back alternator, as pictured sbove in #51. The Mopar alternator is a three phase full wave bridge design, that uses 3 positive polarity diodes and 3 negative polarity diodes. The loss (failure) of any of the diodes will result reduction of capacity (amperage) by HALF of the rated output of the alternator. While under a light electrical load, the voltage will be somewhat normal but under high load, the voltage will be be lower.
            The stator windings produce the AC voltage and are connected in a Y configuration with each of the "arms" of the Y connected to the diodes, which change the AC voltage produced in the stator to DC voltage to operate the vehicle. The rotator produces the magnetic field which the stator windings make the AC voltage.
            The ultimate capacity of the alternator can be changed by using different stator windings and diodes. The original round back alternator uses individual pressed in diodes while the square back design uses smaller but more powerful diodes that are welded to the heat sink bar.
            Changing the capacity of the alternator is not like a Chinese menu where you pick and choose but is usually limited to 2 or 3 amp ranges. Bear in mind that simply increasing the capacity should be coordinated by increasing the capacity of the output wire and bulkhead connections to match the amperage available. Failure to do so usually results in bulkhead connection problems (melting). Its highly likely that your "man" does not know your particular wiring type, size or condition......so proceed with caution. Just my opinion of course.
            BOB RENTON
             
          • Evan Frucht

            Evan Frucht Well-Known Member

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            Ok thanks. I think we may be onto something here with the alternator. I'll keep this updated with the progress. I dont think in gonna change the amperage I dont have any aftermarket stuff going on it should work fine stock.

            The dimming lights thing I would like to fix but it's not the main issue. The main issue (which I think is related) is bad idle and a charging system that is providing about 10.5 when idling in drive with lights on and worse with wipers and high beams.

            Another mystery, which I mentioned earlier....
            My high beams only work for about 2 minutes then they start turning on and off and flashing. If I turn the high beams off things go back to normal. This would happen at idle or even on the freeway with high rpms
             
          • Moparnocar

            Moparnocar Well-Known Member

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            What is your amp gauge doing while this is happening?
             
          • RJRENTON

            RJRENTON FBBO Gold Member FBBO Gold Member

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            Usually, but not always, flickering of the headlights is due to the auto reset circuit breaker on the headlight circuit, due to a high resistance ground somewhere on the high beam wiring. Also, the problem MAY be due to your low voltage causing higher than normal amps to be needed. B4 tearing into the wiring, fix your low system voltage at idle first....low idle speed OR a bad diode in your existing alternator or possibly a bad voltage regulator or brushes in the alternator. These brushes feed the voltage to the rotating field. A bad brush would result in low alternator output voltage. It may be a simple fix....
            BOB RENTON
             
          • Evan Frucht

            Evan Frucht Well-Known Member

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            When I'm at a stop light the needle goes toward the D side. Worse if lights and accessories are on. Otherwise it shows I'm charging.
            I never noticed what it does when the high beams start to flicker out tho
             
          • Evan Frucht

            Evan Frucht Well-Known Member

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            Sounds good. Thanks. We'll see what the doctor says about the condition of my alternator and go from there
             
          • Evan Frucht

            Evan Frucht Well-Known Member

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            Well, my alternator seems to check out. He tested all the diodes and then put it on another machine to test it. It passed the tests fine. He put in some new brushes anyway becuase mine were a little worn. He did this all in front of me. He put it back on his tester after this and said it was better with the new brushes. He didnt charge me for any of this. I will put it back on the car tmrw and see if the new brushes changed anything.

            Assuming it does NOT change I will try turning the idle up even further. I think it's at about 800 when I'm in DRIVE with foot on brake. It rises to about 1000 when I shift into PARK or NEUTRAL.

            What RPM should my idle be at in everyone's experience?

            What's the highest idle speed I should go to? If i go high enough it will solve the problem I'm sure ... but then again I dont want a ridiculously fast idle. I have a timing light to test RPM.

            How fast should the car move forward if I take my foot off the brake. Right now it quickly starts to move 2-3 mph if I take foot of brake. Feels on the faster side of "normal" to me already.

            Even if that does help, I will likely have to address the 0.9v voltage drop. I'm thinking I will need to trace the power from battery to alternator and then address any bad connections. Hopefully it's all somewhat accessible and that it's only a bad connection and not a bad length of wire.

            I also have one of those new electronic voltage regulators coming in the mail which I'm hoping will help.

            Any thoughts ?
             
            Last edited: Dec 3, 2019 at 5:58 PM
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