Posted By: TonyS451
Overcharging problem - question - 03/17/12 03:09 PM
Hey Guys - Have a 67 Coronet wagon with a overcharging problem. Tried 2 new voltage regulators, 2 alternators, new engine wiring harness, sanded down mating surface of voltage regulator to ensure a good ground (with strap to engine) and still overcharging. It will pin the gauge needle to the charge side (18v) on aftermarket gauge and does the same with the factory dash gauge. It has also been confirmed on a auxillary gauge that it is in fact overcharging.
Havn't found any obvious wiring mixups, so I'm a little stumped as to why I still have an overcharging issue. Would it be easier to just get an internally regulated alternator, or is that just a band aid for a potential wiring problem?
What are your thoughts? Thanks
Posted By: Andrewh
Re: Overcharging problem - question - 03/17/12 03:17 PM
well based on what you replaced, the bulkhead connector would be the next logical place to look.
but lets backtrack a little and see if any of that was necessary.
first what is the sensing voltage to the voltage reg with the key in run?
next what does your battery read with the car off as well?
use the negitive of the battery as the ground for both, then just incase there is a difference, use the firewall where your vr is grounded and see what it reads as well.
If they are not equal, the trace back to the bulk head and read on the engine side and then the interior side and see what the readings are with the car in run.
I bet you find a difference there.
feets car saw over 2 volts difference and I wired up a relay instead to power the vr and balast and it worked fine after that.
Posted By: 79powerwagon
Re: Overcharging problem - question - 03/17/12 03:39 PM
I too had an overcharging issue, tried several new VR trying to find out the problem. Someone here asked if I was using a Mopar piece or a Wells (or other aftermarket unit). I was using aftermarket. They suggested I use a real Mopar, and the problem went away and never returned.
Just another idea.
Posted By: RapidRobert
Re: Overcharging problem - question - 03/17/12 03:40 PM
Wiring prob. Disconnect ALL field wires then use jumper wires with alligator clips to connect batt positive to reg "ign". Jump connect reg "field" to alt field terminal. You're sure the alt/reg are grounded to batt neg properly. See if it behaves now & if so that'll confirm that it is a wiring prob. If not then the alt or the reg (more likely) is it. mechanical or electronic reg? Could have gotten a bad reg. If you confirm it is wiring then replace 1 jumper at a time with its OE lead till you find the culprit. Do the one at a time wiring changes with the eng off. I'm assuming your batt is fully charged and the large cables/batt terminals (positive an neg circuits) are cleaned. Sure sounds like a bad reg, something is full fielding it. EDIT do not go w an internally regulated alt
Posted By: John_Kunkel
Re: Overcharging problem - question - 03/17/12 08:49 PM
I know the OP states it's a '67 but does it have the original single field connection alternator or has it been upgraded to a dual field connection alternator?
Posted By: 71yelladustr
Re: Overcharging problem - question - 03/17/12 09:52 PM
What does it charge with the voltage regulator unplugged? If it is still overcharging even while unplugged, the green field wire to the regulator is shorted to ground.
Posted By: markz528
Re: Overcharging problem - question - 03/17/12 10:04 PM
Check the voltage regulator ground. If the ground is poor it will think the voltage is lower than it really is.
Posted By: jamesc
Re: Overcharging problem - question - 03/17/12 11:13 PM
on the newer two wire charging system the regulator controls the ground to vary the output. the field circuit makes a magnetic field in the rotor of the alternator, by controlling the strength of this field it controls the output. one side of the field sees ignition positive voltage and the regulator controls the ground side to vary the output. if the ground side is shorted to ground anywhere it will produce maximum output.
Posted By: John_Kunkel
Re: Overcharging problem - question - 03/17/12 11:31 PM
Disconnect the ground control field wire (usually green) from the alternator terminal, if it stops overcharging the wiring is the problem. Check the control wire for a short to ground between the alternator and regulator.
If it still overcharges with the wire off there is an internal short to ground.
Posted By: RapidRobert
Re: Overcharging problem - question - 03/18/12 03:23 AM
on the 2 field circuit system you pretty much just need switched 12V via the blue wire circuit to (1) the the top terminal in the VR triangle connector with the "top" being with the triangle being "up" like a pyramid and (2) T ing off of it to either one of the male alt field terminal (blue wire). Then the green wire runs from the "side" VR terminal to the other alt male field terminal. Is that what you currently have wired? That's all you need for the field circuit to make it charge
Posted By: Andrewh
Re: Overcharging problem - question - 03/19/12 12:03 AM
that depends.
does that line read some small voltage, or ground?
if it reads ground, you have a break in the line somewhere and you need to trace it back to the vr from the alt.
if it reads voltage of some sort, then you need to check voltage on the other line plugged into the alt and see if it reads voltage or ground.
again, ground, would mean a break, voltage on both means bad vr, or bad voltage to the vr as I said in the begining.
Posted By: jamesc
Re: Overcharging problem - question - 03/19/12 12:26 AM
that proves there isn't an internal short. that line could be shorted to ground, the VR may not be seeing the +12 ignition, the VR could be bad or have a bad ground. this is a very simple circuit, here's a link
mopar charging system
Posted By: John_Kunkel
Re: Overcharging problem - question - 03/19/12 09:21 PM
If it's overcharging, both the regulator and alternator are getting battery voltage.
Since both the alternator and the regulator have been changed twice it's pretty safe to say there is a short in the field wire between the alternator and the regulator; most common place is where it runs along the valve cover.
Posted By: 75DART440
Re: Overcharging problem - question - 03/20/12 05:04 AM
I once saw a parts store reman alternator that was missing the small insulating washers under the field terminals. It overcharged untill it cooked the fuse link and the alternator.
Posted By: superbeedave
Re: Overcharging problem - question - 03/20/12 05:43 AM
Just from my experience I had some 13 years ago! After I bought my 69 Superbee I bought a carter 625 carb. and Mopar electronic ignition. Two or so years later I started noticing battery acid running out of my battery. I put voltage meter on for the first time and it was charging 15.2 volts. And this was 10 or so years ago. I had this overcharging problem for some eight years. Man, you talk about frustrations! I ended up going to a 70's style charging system and that brought it down a little but still had the problem until I bought a new 650 AVS carburetor two years ago. After I had my engine rebuilt it was again up to 15.2 volts. Well when I started going over the instructions I read where it said DO NOT!! hook the hot wire from the electric choke to positive side of coil! Well for those years I had it hooked up to the coil but when I hooked up the new carb. choke wire to key on pos. wire my voltage came down to normal, after all those years! That was my problem, go figure! So I'm just saying do you have an electric choke and if you do is it hooked up to either your ballast resistor pos. side or coil side?
