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Thread: Quick question regarding voltage regulator

  1. #1
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    Quick question regarding voltage regulator

    I've got a 60 Lark VI retrofitted with an alternator and Chrysler voltage regulator. My question is, does the regulator housing need to be mounted to the frame (grounded) or isolated from the frame? I ask because I replaced it along with a bunch of other components the other day, and when I got my car started--a miracle, if you follow my other threads--my headlights would flicker and my idle was slightly slower when I mounted it to the frame, but it smoothed out and the flicker went away when I isolated it. The old one didn't do this before, so I reinstalled it both ways, and it has the same symptoms now; clearly something changed when I replaced the solenoid and ballast resistor. Before someone asks, yes, I made sure that all my connections were correct when I swapped those components.

    Now, since then, I have had my battery tested as bad and replaced it today along with my battery cables. When I ran the car, the battery voltage only read 12.5v, even while revving higher than idle. Since then, I discovered that the ground wire on the passenger side, for the engine, was missing so I installed a replacement. I haven't had a chance to retest the alternator since, thinking I might remove it and have it checked out, but after finding the ground strap missing, and testing resistance before and after--a change from a 1-15 ohm reading to a 0.1-0.5 ohm reading--I'm wondering if I should reinstall the regulator to the frame.

    I have tried to find opinions elsewhere online, but found conflicting information. Anyone care to share their insights?

  2. #2
    President Member TWChamp's Avatar
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    I've never seen an external voltage regulator that didn't need a ground. Is the alternator a MoPar part?

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    Quote Originally Posted by TWChamp View Post
    I've never seen an external voltage regulator that didn't need a ground. Is the alternator a MoPar part?
    I don't know. Came with the car, but it's not marked anywhere I can see.

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    If I ground the regulator, the voltagetsg measured at battery is 15.5v. If I isolate it, 12.7v. Obviously the battery isn't getting charged when the regulator isn't ground, but if it is grounded, all of my lights pulsate. When it's isolated, they remain steady. Is it possible my new regulator is a dud?

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    The voltage regulator has to be grounded for it to function correctly. If the voltage is fluctuating, then you have might have a bad regulator, but before you condemn the regulator, recheck all of your connections and be sure you have a good ground between the engine and the body. I like to add a ground wire between the engine block and the body because I don't trust the ground connections between the frame and body on a car that is almost 60 years old. Also have the alternator tested as you could have a problem such as a bad diode. Bud

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    Quote Originally Posted by Bud View Post
    The voltage regulator has to be grounded for it to function correctly. If the voltage is fluctuating, then you have might have a bad regulator, but before you condemn the regulator, recheck all of your connections and be sure you have a good ground between the engine and the body. I like to add a ground wire between the engine block and the body because I don't trust the ground connections between the frame and body on a car that is almost 60 years old. Also have the alternator tested as you could have a problem such as a bad diode. Bud
    If you'll review my previous posts, added an engine ground, and provided my resistance readings before and after. Connections were checked throughout and many cables were replaced as well as most of the ignition system components.

    Is testing the alternator something I can do beyond the voltage test, or am I going to need to take it to a shop?

  7. #7
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    Auto Zone can test alternators and other electronic components. Other parts stores can also. -Jim

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    Everything seems to be in order now. Alternator tested good at AutoZone.

    I installed a new regulator and I tested for the following:

    Engine to frame: <1ohm
    Alternator to engine: <1ohm
    Alternator to frame: <1ohm
    Regulator to frame: <1ohm
    Voltage at battery at idle: 14.5v

    The high idle is a bit too high, but I'll make that adjustment when the engine cools. For now, everything seems to be fine. Gonna have to keep an eye on the battery though. It's a 3-year battery from O'Reilly, but it lasted only about six months. Could be the old regulator killed it, but I'm now suspicious.

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    It appears to me that you have solved the problem. 14.5 volts is within spec so you're good there. I've had trouble with the late model replacement Chrysler regulators. They don't have a very long life if they work to begin with. I've been buying NOS or NORS electrical parts from EBAY and swapmeets for years and have had a bunch better luck with the parts. Bud

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