Charging problem.

Discussion in 'Sparky's corner' started by 1adam12, Jul 2, 2018.

  1. 1adam12

    1adam12 Well-Known Member

    I have a 67 gs340 that is having some odd charging problems. It started with a gen light that came on. I checked voltage across the battery it was 16.2. So I figured the regulator took a crap so I went and bought the vr715 digital one to replace it. Installed regulator and no change. So at this point I figured I would take the alternator in and get checked. Alternator check alright so I swapped the regulator for another one. While it was a part I added a ground from the regulator to the alternator and cleaned all the other grounds and put it back together. Still the same. Gen light on and still over charging. I checked for continuity of the brown wire from regulator to the ignition switch and Blue wire to the alternator. All showed no resistance. The other odd thing is that when you turn the key to run the gen light does not come on as it should. Thanks guys I am no electrician just stumbling my way through this
  2. TrunkMonkey

    TrunkMonkey Well-Known Member

    Make sure you have the following.
    A good ground from the battery to the engine.
    A good ground from the battery to the frame.
    A good ground from the engine to the body.
    (And I add a ground from body to frame.)

    Then check dash to body, as that is how the instument panel printed circuit board grounds and that effects lights and indicators.
    As well as the switches and electrical controls.

    Otherwise you can have ground loop problems.

    Almost all the circuits rely on power to ground through the "device" and the frame/body back to the battery negative terminal to complete these circuits.

    When you have "bad grounds" the current "seeks" to find ground, and what often happens is greater amps flowing/back flowing through circuit to reach ground.

    This can result in any/everything from odd behavior of accessories and devices, to non working, or failure of same, and worst, wire fires.

    Electrical wiring on autos is not complicated, but it is complex, and often requires looking, tracing circuits several times, and actually tracing and following the physical wires along with the schematics.

    Patience is your best ally.

    And to add to the complexity is the "50" years that all of this has been in use, corrosion, and oxidation of copper raising resistance and impeding conductivity.

    Not to forget the "previous owner(s)" ham handed involvement of screwing up wiring.
  3. 1adam12

    1adam12 Well-Known Member

    Thanks what's size grounds should I run and what is the best way to ground the dash
  4. 1adam12

    1adam12 Well-Known Member

    Ok guys had some time to work on car tonight. I had alternator checked and battery to be sure. Both tested fine. So I started checking grounds. I went from the negative cable to engine,core support,alternator, and chassis. All show continuity with minimal resistance. I then checked from the negative battery cable to the positive battery cable and I show no continuity. I would think the starter should ground through the block. I also noticed that I am only getting 3.5 volts to the coil and when it's running the tachometer needle bounces around like crazy. Any ideas to check. Electrical is not my strong suit for sure
  5. stellar

    stellar Well-Known Member

    check fuse. A bad fuse will cause no lite with key on and lite on when running. check wires for voltage at regulator plug. Plug reads left to right F,1,2,3. The right end one (3) should have voltage with key on and no power with key off. The one next to it (2) should have power at all times.
    Last edited: Jul 31, 2018
  6. 72STAGE1

    72STAGE1 Runnin' with the Devil

    I had the exact problem for a year, bought 2-3 made in America $78 regulators, alternators, battery's ect....Then I went with the cheap $29 electronic voltage regulator made in China and solved the problem.....and no I still can't figure it I don't care now .
  7. TrunkMonkey

    TrunkMonkey Well-Known Member

    Check the resistance wire. You should have around 8-9 volts for breaker points distributor. If you have HEI or electronic distributor, post the make/model of that.

    You could start the car then attach a 12V wire source to the positive side of the coil for a few minutes to see if that steadies the tach.

    As for the overcharge, even though the alternator checks at the parts store, if the sensing wire back to the battery is not energizing, the alternator will continue to stay in a high state thinking it needs to charge the low voltage state of the battery. This is only a guess since you have gone through the original (as you got the car) and two other regulators with no change and the wiring appears to be correct.

    The ignition switch is grounded to the dash, the dash is the ground for most everything in the dash.
    I would loosen and then tighten the bezel ring for the ignition switch to re-establish its ground.
  8. 72STAGE1

    72STAGE1 Runnin' with the Devil

    I believe its a Alternator thing, as if some new way they are rebuilding them isn't compatable with old stuff, of even possibly the Voltage regs. themselves, because this problem exists on my car, my sons, and many others on here and we did nothing to change things per se.......
    TrunkMonkey likes this.
  9. 1adam12

    1adam12 Well-Known Member

    Ok check all wires from the fuse lock out to engine. All checked fine. The resistance wire checked out fine. I forget the exact resistance but my reading was in the range I found in the service manual. The odd thing is if I check voltage at battery. I get over 16. If I check the horn relay I get over 16. I I check lug on back of alternator I get 14.7. How is this possible. Thank you to all for the help. This is why I love this site all the wonderful people who make up the community v8 buick.
  10. stellar

    stellar Well-Known Member

    Can you tell me what the voltage is at the regulator plug when unplugged from the regulator with key on engine off at terminal 3 and 4 of the plug?
  11. 1adam12

    1adam12 Well-Known Member

    Sorry Stellar for taking so long. I got a chance to mess with the car tonight terminal 3 red wire is 14.03 and terminal 4 brown wire is 12.21 battery voltage was 14.27. I thought I found the problem the positive coil wire had gotten pinched between the bracket and block on a coil replacement couple months ago. I repaired the wire and rehooked everything back up thinking this was my short. Needless to say it solved my random engine miss and crazy tach but it's still over charging.
  12. 65specialconver

    65specialconver kennedy-bell MIA

    Check voltage both at the ring terminal of the cable of both sides of the battery and then on the posts themselves.Sounds like a simple poor battery might be overlooking the simple fix
  13. 1adam12

    1adam12 Well-Known Member

    Battery cables are new I get same voltage reading at battery post and on cables themselves. I also see same voltage at main splice, horn relay, and back post of alternator. Starting to pull my hair out thought I found it yesterday with the short at coil.

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