Going crazy with new Duster and over voltage issue.

[ultimatejay]

Hi everyone, new member here. Just bought a good condition 1970 Duster with 225 slant 6 that has supposedly 85k original miles for my son and i to work on. Drove it home 60 miles and then about 5 miles from home it started running rough/backfire/stalled. Got it started and limped it home. Once home the engine would not start and when it did it ran rough. Long story short I found the ignition condensor failed due to overvoltage. I put new condensor and checked battery voltage and found 16-17 volts and battery was fizzing out of vent! The previous owner just put in a new alternator, cap, rotor, points but did not replace the voltage regulator. So i went to local auto parts and bought what was in stock which was a POS china crap. Installed it and it did help dropping it down to 15-15.4 volts which is still too high. Did search here and checked some things recommended by other members. What i have checked
1. voltage regulator ground is good
2. Tried another known good battery- same issue
3. disconnected field terminal and /VR terminal and charging stopped
4. REmoved bulkhead connectors at firewall and looked and cleaned them. They all look pretty good- no corrosion
5. Checked and cleaned all grounds. Although i did notice there is no ground cable from block to firewall. There is a small ground off main battery ground that goes to front radiator support. I assume this is the ground for the chassis or is there supposed to be another from engine to firewall?
6. I tested field wire to positive battery cable with key on engine off and had 1.2 volts. I assume this is my issue as i have a voltage drop from wiring somewhere? If that is the case, where to go from here to find the issue? Also, I had similar issue with my Chevy c10 and i went through 2 china alternators and 2 VRs until i someone told me to get a solid state VR and that solved my issue so I'm worried my new china VR might not be up to par. Please help me I have been messing with this for 2 days now. This is my first Mopar so I'm green on knowing where everyting is. Thanks for any help

 

[Dana67Dart]

5. Checked and cleaned all grounds. Although i did notice there is no ground cable from block to firewall. There is a small ground off main battery ground that goes to front radiator support. I assume this is the ground for the chassis or is there supposed to be another from engine to firewall?

1st thing... Get a good heavy ground strap from block to body. Without it the current while starting has to find a path and it will go through any path it can find, through the transmission, the tailpipe, the gear shifter, etc.

 

[Joey4speed]

Try clamping jumper cables from engine block to chassis ground, to see if voltage changes.

 

[ultimatejay]

1st thing... Get a good heavy ground strap from block to body. Without it the current while starting has to find a path and it will go through any path it can find, through the transmission, the tailpipe, the gear shifter, etc.

Ok, thanks I will do that first thing in the morning.

 

[Dana67Dart]

Does the negitave battery cable go to the head or intake bolt,or just to the front rad support?

 

[ultimatejay]

Does the negitave battery cable go to the head or intake bolt,or just to the front rad support?

The main large negative cable goes to the cylinder head right on top of the a/c bracket. then there is a smaller 8-10 gauge wire that goes to the front radiator support just in front of the battery tray.

 

[ultimatejay]

I saw a video where a guy used a meter and had it set to 20k ohms and bench tested the Voltage regulator across the two terminals and he said it should be 1.75. Well both my China regulators measure 3.5

 

[67Dart273]

The most common cause of overcharge/ over voltage in these girls is VOLTAGE DROP in the electrical harness, and or drop in the ground path from battery to VR

HOW to check:

With key in "run" but engine stopped, connect one multimeter probe to the "key" switch feed on the ballast resistor. If in doubt, measure both ends of the ballast to ground--you want the one with the highest reading. Now connect the other probe --stab it into the top of the battery PLUS post. You are hoping for a very very low reading, and if it is more than about .3V you have a drop problem and need to look for it

Check the ground: With engine warm, and battery charged as normal as you can get it, run the engine at fast idle. Make this test first with all accessories off, and again with heater, lights, etc powered on

Stab one probe of your meter into the top of the battery NEG post. Stab the remaining probe into the mounting flange of the VR. Be sure to stab through rust, paint, etc. You are again hoping for a very low reading, the lower the better, and zero is perfect. If not upgrade the grounding from engine block to firewall

If you do not have a service manual, wander over to MyMopar and download one--free. You may have to settle for Dodge vs Plymouth, etc

 

[67Dart273]

HOW THESE WORK The 70/ later VR controls the "amount of ground" that the field sees. There are two field wires to the alternator, one is switched 12V from the key, and the green wire returns to the VR, which grounds the green "more and more" as more charge is called for.

Pull the connector, inspect the connector and VR pins for corrosion, and push it in/ out several times to "feel" for tightness and to 'scrub" the terminals clean.

Another thing you can do in relation to the above tests, is to jumper a nice big say, no16 or 14 alligator clip lead from the battery (or the starter relay "big stud") direct to the "key" side terminal of the ballast. Clip it under the connector on the ballast and leave everything connected. See if your charge voltage goes down to normal, about 13.5--14.2

ALSO VR voltage is TEMPERATURE SENSITIVE so warm up the engine. If you get a service manual, there is a temp vs voltage chart somewhere there in section 8 of the charging system

"Common causes" and can be a combination: Voltage drop at ANY terminal in the path between battery and VR: From starter relay "big stud"----fuse link---through bulkhead connector on big RED ammeter wire--to and through ammeter---out big BLACK ammeter wire--to WELDED SPLICE (in black wire near cluster) ---power feed to IGNITION SWITCH connector---through switch and back out on IGN1 (usually dark blue) and through SWITCH CONNECTOR---back out through bulkhead and to BALLAST RESISTOR

 

[ultimatejay]

The most common cause of overcharge/ over voltage in these girls is VOLTAGE DROP in the electrical harness, and or drop in the ground path from battery to VR

HOW to check:

With key in "run" but engine stopped, connect one multimeter probe to the "key" switch feed on the ballast resistor. If in doubt, measure both ends of the ballast to ground--you want the one with the highest reading. Now connect the other probe --stab it into the top of the battery PLUS post. You are hoping for a very very low reading, and if it is more than about .3V you have a drop problem and need to look for it

Check the ground: With engine warm, and battery charged as normal as you can get it, run the engine at fast idle. Make this test first with all accessories off, and again with heater, lights, etc powered on

Stab one probe of your meter into the top of the battery NEG post. Stab the remaining probe into the mounting flange of the VR. Be sure to stab through rust, paint, etc. You are again hoping for a very low reading, the lower the better, and zero is perfect. If not upgrade the grounding from engine block to firewall

If you do not have a service manual, wander over to MyMopar and download one--free. You may have to settle for Dodge vs Plymouth, etc

When i check voltage at ballast resistor i get the same voltage on both ends. Also with key on and testing voltage at ignition lead to coil Im getting 12v. This means the ballast resistor is bad correct? Also, would this cause the high voltage charge issue?

 

[hotrod swinger]

Contrary to popular belief, the ballast resistor is rarely the problem, nor is the voltage regulator. It’s probably a connection problem, possibly more than one connection.

What voltage did you measure between key switched feed at ballast resistor and battery positive? As mentioned above, more than 0.3 V is a significant drop in the ignition circuit that requires investigation.

If you measure a 1.5 V drop, this may give you a charging voltage of ~16 V because the voltage regulator will think the system is running 1.5 V lower than it actually is.

If your measurement is higher than 0.3 V follow the path Del (67dart273) outlined above and measure each connection in your ignition circuit.

The drops add up and are cumulative. For example, you may have 0.3 V at the bulkhead, 0.5 V in the ignition switch connector, and 0.4 V in the ignition switch itself, for a total of 1.2 V.

I worked through this same issue earlier this year with Del’s assistance and it turned out to be a cumulative problem, most significant drops were the ignition switch connector and the ignition switch. It’s important to do the measurements.

 

[Syleng1]

Please remember you are dealing with a 50 year old car regardless of mileage. So every connection could be dirty, and or corroded / loose.
Every item has been touched by human hands more than once…. Double check everything. Also, get a copy of the wiring diagram from that particular car. Learn to read it properly. These systems are simple when you understand how they actually work. We are all guessing to help you based on what we have experienced in our past.
A few pictures help also. Lots of people on here have keen “eagle like” eyes and can spot issues just from some well taken photos or video. Good luck.

 

[Mattax]

Although i did notice there is no ground cable from block to firewall. There is a small ground off main battery ground that goes to front radiator support. I assume this is the ground for the chassis or is there supposed to be another from engine to firewall?

My recollection is the body grounding changed areoun 1970. Early cars had battery to engine, then engine to firewall on the passenger side. Around '70 the battery negative also got a a 12 ga ground to body.

I tested field wire to positive battery cable with key on engine off and had 1.2 volts

On a '70 you must measure the blue field wire. Another place to check is at the ballast resistor blue wire connection.
Assuming you did that, then yes too much resistance as explained earlier in this thread.

When i check voltage at ballast resistor i get the same voltage on both ends.

It will be the same when there is no current flowing through it. Voltage only drops when current goes through a device or a poor connection.

For example, if there are three light bulbs connected in a row to a battery.
When the switch is open the voltage in at any point will be battery voltage.
Close the switch, and voltage will be lower on the other side of each bulb. After the last bulb the voltage will be zero.

Also with key on and testing voltage at ignition lead to coil Im getting 12v

See above.

This means the ballast resistor is bad correct?

No.

Also, would this cause the high voltage charge issue?

See the explanation from 67Dart273. This is the main point.

If you measure a 1.5 V drop, this may give you a charging voltage of ~16 V because the voltage regulator will think the system is running 1.5 V lower than it actually is.

This schematic shows the main circuits of interest.

The main splice (black dot) connects the two power sources to the wires feeding everything else.
The battery provides power at most, at 12.8 Volts
When the alternator is running, it provides power at 13.8 - 14.8 Volts.
Any and all resistance to flow between the alternator output and the regulator's sensing terminal (connects to wire J2B) will cause over the regulator to atttempt to up the voltage.

Observe the ammeter too. It shows current flow in or out of the battery, fo amps out to 40 amps in. Straight up is zero. That's where it should be after recharging the battery.

 

[Mattax]

Please remember you are dealing with a 50 year old car regardless of mileage. So every connection could be dirty, and or corroded / loose.
Every item has been touched by human hands more than once…. Double check everything. Also, get a copy of the wiring diagram from that particular car. Learn to read it properly. These systems are simple when you understand how they actually work. We are all guessing to help you based on what we have experienced in our past.
A few pictures help also. Lots of people on here have keen “eagle like” eyes and can spot issues just from some well taken photos or video. Good luck.

Yup!
Posted some photos of damage in my wagoneer's alternator output wire last night. Ring terminal itself looked good, but some heat damage and a nick to the insulation had resulted in oxidation and even a little corrossion over time. Here's the one after I slit open the damaged insulation. (Its wet from the Deoxit).

 

[67Dart273]

When i check voltage at ballast resistor i get the same voltage on both ends. Also with key on and testing voltage at ignition lead to coil Im getting 12v. This means the ballast resistor is bad correct? Also, would this cause the high voltage charge issue?

No it means that you happened to measure that voltage when the breaker points are open. There is no current flowing through the ballast, so the voltage is the same. If you "bump" the engine so the points are closed, you should read "same as battery" at the "key" end and much lower at the "coil" end, say, 5-10V or so. But that is not what you need to check to test for drop. Please re-read the specific instructions in my post. What you are trying to do here, is to determine the drop from battery PLUS post to the "key" supply terminal of the ballast. The reason for that, is that nearby in the harness, that "ignition run" supply wire--coming from the ignition switch --- branches off and feeds several items, depending on the year/ model of the car............

Feeds ballast and to coil
Feeds VR IGN terminal
Feeds the blue wire going to alternator field
Feeds electric choke if used
Feeds idle solenoid if used
On some models (later) feeds a smog doo-dad or two

All these items draw power and the current loads and stresses the terminals, connectors, and switch(s) in series with the path from the battery to the VR. You are trying to determine if this is so, how bad it is, and after that, you will need to backtrack that path and find the culprit

READ this article from MAD about the cause of bulkhead connector problems. If you don't do this bypass, the article makes some good points as to the cause, etc. ALSO THIS SIMPLIFIED diagram shows you most of the path I am talking about:

What is not shown here is "the rest of the path"..... From the wire labeled "to igntion switch" that goes to the switch CONNECTOR, through the SWITCH, back out the switch connector on the IGNTION RUN wire, back out through the BULKHEAD connector, and to the ballast, and branch of to the VR, etc.

Each one of those points with a terminal/ switch/ connector is a drop "suspect."

You must measure voltage ACCURATELY. Don't just look for "some voltage" measure it to tenths or hundredths. Check both sides of the key switch connector on the power coming TO the key and to the ignition run LEAVING the key. Leave everything connected, key in "run" when doing this so that you have CURRENT flowing. CURRENT is what causes drop through "poor" connections.

If the power going TO the key switch is less than battery, you have a drop through the red/ black ammeter circuit TO the key.

IF that reading to the ignition switch infeed are OK, and the "run" line going back out are OK, then it has to be in the bulkhead connector in the "ignition run" wire. This is not difficult, it's just like a road map. Where is it muddy? What road? Where on that road? Is it "muddy" between the turn off and your mail box? Etc.

Catalog

 

[ultimatejay]

Contrary to popular belief, the ballast resistor is rarely the problem, nor is the voltage regulator. It’s probably a connection problem, possibly more than one connection.

What voltage did you measure between key switched feed at ballast resistor and battery positive? As mentioned above, more than 0.3 V is a significant drop in the ignition circuit that requires investigation.

If you measure a 1.5 V drop, this may give you a charging voltage of ~16 V because the voltage regulator will think the system is running 1.5 V lower than it actually is.

If your measurement is higher than 0.3 V follow the path Del (67dart273) outlined above and measure each connection in your ignition circuit.

The drops add up and are cumulative. For example, you may have 0.3 V at the bulkhead, 0.5 V in the ignition switch connector, and 0.4 V in the ignition switch itself, for a total of 1.2 V.

I worked through this same issue earlier this year with Del’s assistance and it turned out to be a cumulative problem, most significant drops were the ignition switch connector and the ignition switch. It’s important to do the measurements.

No it means that you happened to measure that voltage when the breaker points are open. There is no current flowing through the ballast, so the voltage is the same. If you "bump" the engine so the points are closed, you should read "same as battery" at the "key" end and much lower at the "coil" end, say, 5-10V or so. But that is not what you need to check to test for drop. Please re-read the specific instructions in my post. What you are trying to do here, is to determine the drop from battery PLUS post to the "key" supply terminal of the ballast. The reason for that, is that nearby in the harness, that "ignition run" supply wire--coming from the ignition switch --- branches off and feeds several items, depending on the year/ model of the car............

Feeds ballast and to coil
Feeds VR IGN terminal
Feeds the blue wire going to alternator field
Feeds electric choke if used
Feeds idle solenoid if used
On some models (later) feeds a smog doo-dad or two

All these items draw power and the current loads and stresses the terminals, connectors, and switch(s) in series with the path from the battery to the VR. You are trying to determine if this is so, how bad it is, and after that, you will need to backtrack that path and find the culprit

READ this article from MAD about the cause of bulkhead connector problems. If you don't do this bypass, the article makes some good points as to the cause, etc. ALSO THIS SIMPLIFIED diagram shows you most of the path I am talking about:

What is not shown here is "the rest of the path"..... From the wire labeled "to igntion switch" that goes to the switch CONNECTOR, through the SWITCH, back out the switch connector on the IGNTION RUN wire, back out through the BULKHEAD connector, and to the ballast, and branch of to the VR, etc.

Each one of those points with a terminal/ switch/ connector is a drop "suspect."

You must measure voltage ACCURATELY. Don't just look for "some voltage" measure it to tenths or hundredths. Check both sides of the key switch connector on the power coming TO the key and to the ignition run LEAVING the key. Leave everything connected, key in "run" when doing this so that you have CURRENT flowing. CURRENT is what causes drop through "poor" connections.

If the power going TO the key switch is less than battery, you have a drop through the red/ black ammeter circuit TO the key.

IF that reading to the ignition switch infeed are OK, and the "run" line going back out are OK, then it has to be in the bulkhead connector in the "ignition run" wire. This is not difficult, it's just like a road map. Where is it muddy? What road? Where on that road? Is it "muddy" between the turn off and your mail box? Etc.

Catalog

View attachment 1715846768

Got it thanks, you were right the points were open. So with key on and meter from positive post on battery to IGN lead at ballast im getting .65 which isnt terrible. So now I will check for voltage drops as you mentioned. Like i said I checked the bulkhead connections and they look good so I will check ammeter and ignition switch and go from there. Thanks.

 

[67Dart273]

Got it thanks, you were right the points were open. So with key on and meter from positive post on battery to IGN lead at ballast im getting .65 which isnt terrible. So now I will check for voltage drops as you mentioned. Like i said I checked the bulkhead connections and they look good so I will check ammeter and ignition switch and go from there. Thanks.

OK the voltage you measure--whatever it is--ADDS to the VR setpoint. So "let's say" that after warming up, the VR is at 13.8. That .65 adds to the VR setpoint and "in theory" (and if there is no drop in the ground side) the VR will run the battery to 13.8 + .65 = 14.45. Now that is not "terrible" and if that is true there might be something else wrong. The VR might be out of spec which is not common but can happen. There MIGHT be drop right at the VR terminals/ connector. If you order yourself a rifle cleaning brush for .177 (bb gun/ pellet size) that will fit inside those connector terminals.

THE OTHER issue that might be happening here is that the drop MAY BE CHANGING that is "say" a bad terminal in the bulkhead connector, movement from you removing/ checking/ re inserting the connector may have changed the problem. Vibration/ movement may change it, and if it's in the ignition switch just wiggling the key migiht change "the problem"

 

[ultimatejay]

OK the voltage you measure--whatever it is--ADDS to the VR setpoint. So "let's say" that after warming up, the VR is at 13.8. That .65 adds to the VR setpoint and "in theory" (and if there is no drop in the ground side) the VR will run the battery to 13.8 + .65 = 14.45. Now that is not "terrible" and if that is true there might be something else wrong. The VR might be out of spec which is not common but can happen. There MIGHT be drop right at the VR terminals/ connector. If you order yourself a rifle cleaning brush for .177 (bb gun/ pellet size) that will fit inside those connector terminals.

THE OTHER issue that might be happening here is that the drop MAY BE CHANGING that is "say" a bad terminal in the bulkhead connector, movement from you removing/ checking/ re inserting the connector may have changed the problem. Vibration/ movement may change it, and if it's in the ignition switch just wiggling the key migiht change "the problem"

Thanks for the help. So I didnt like the small ground from battery negative cable to front core support so i put another short battery ground from engine block to firewall. I also ditched the old china crap VR and went and bought a mopar performance VR. After looking at everything it appears the hack that was working on this car before i bought it put a 10 gauge wire front the alternator output directly to the starter relay to battery with no fuse or fusible link. After all that, with the engine warm it now is charging at 14.3 volts. I can live with that for now until i have more time to locate the small voltage drop in system. I think the battery got damaged from the overvoltage because when i turn the engine off the battery voltage will be at 14 volts and then slowly drop down to 13.3. I know theres a surface charge but that seems pretty high?

 

[67Dart273]

No that would be normal. That charge voltage is just fine. Measure battery voltage after a couple hours of sitting dormant, or else run the headlights a couple minutes with engine shut off and see what that gets you. What you have now does not seem too bad A healthy fully charged battery is about 12.6 but this varies a little and with temperature

Another way to get an idea of battery "health" is to disable the ignition, and crank the starter for about 15 seconds while monitoring the battery voltage. The higher the better, but if it's above 10.5 consider it "GOOD"

One thing I've recommended as a "work around" for the ignition / VR "run" line to "fix" that is to cut the "run" (normally dark blue) where it comes out of the bulkhead. Use the bulkhead side to trigger a (such as) Bosch relay, and connect the engine bay end of the blue to the switched relay contacts. Feed the relay with a fuse/ breaker off the start relay "big stud." On a side note you can run the relay coil ground connection in through an unobtrusive switch to ground and create a simple anti-theft device.

 

[Mattax]

They way you have it wired now, if you see the ammeter showing discharge when driving with the lights, wiper, or heater fan on,
a) then its likely there's resistance in the factiry line from the alternator to the main splice.
b) If that's more than halfway toward 40 amps, fix that sooner than later. Continuously running more 25 or more amps through the 16 gage fusible link may cause it and its connections to get hot...

 

[ultimatejay]

No that would be normal. That charge voltage is just fine. Measure battery voltage after a couple hours of sitting dormant, or else run the headlights a couple minutes with engine shut off and see what that gets you. What you have now does not seem too bad A healthy fully charged battery is about 12.6 but this varies a little and with temperature

Another way to get an idea of battery "health" is to disable the ignition, and crank the starter for about 15 seconds while monitoring the battery voltage. The higher the better, but if it's above 10.5 consider it "GOOD"

One thing I've recommended as a "work around" for the ignition / VR "run" line to "fix" that is to cut the "run" (normally dark blue) where it comes out of the bulkhead. Use the bulkhead side to trigger a (such as) Bosch relay, and connect the engine bay end of the blue to the switched relay contacts. Feed the relay with a fuse/ breaker off the start relay "big stud." On a side note you can run the relay coil ground connection in through an unobtrusive switch to ground and create a simple anti-theft device.

Good idea and thanks for all your guys help. I just drove the car 20 miles and it ran perfect. Cant believe how smooth this slant 6 runs. i monitored the charge voltage several times during the drive and it was between 13.7 to 14.1 volts, so it seems pretty good now. One odd thing is that the fuel gauge was reading fine yesterday but today it seems to be stuck past the full mark. When i turn engine off it goes back down and when i turn ignition back on it goes to past full mark so i have a wiring/ sender unit issue there. Its never ending with these old cars lol

They way you have it wired now, if you see the ammeter showing discharge when driving with the lights, wiper, or heater fan on,
a) then its likely there's resistance in the factiry line from the alternator to the main splice.
b) If that's more than halfway toward 40 amps, fix that sooner than later. Continuously running more 25 or more amps through the 16 gage fusible link may cause it and its connections to get hot...

I will keep an eye on it, thanks for the heads up

 

[ultimatejay]

No that would be normal. That charge voltage is just fine. Measure battery voltage after a couple hours of sitting dormant, or else run the headlights a couple minutes with engine shut off and see what that gets you. What you have now does not seem too bad A healthy fully charged battery is about 12.6 but this varies a little and with temperature

Another way to get an idea of battery "health" is to disable the ignition, and crank the starter for about 15 seconds while monitoring the battery voltage. The higher the better, but if it's above 10.5 consider it "GOOD"

One thing I've recommended as a "work around" for the ignition / VR "run" line to "fix" that is to cut the "run" (normally dark blue) where it comes out of the bulkhead. Use the bulkhead side to trigger a (such as) Bosch relay, and connect the engine bay end of the blue to the switched relay contacts. Feed the relay with a fuse/ breaker off the start relay "big stud." On a side note you can run the relay coil ground connection in through an unobtrusive switch to ground and create a simple anti-theft device.

You wouldnt happen to have a wiring diagram on wiring the ign run relay would you?

 

[ultimatejay]

LIKE THIS RIGHT?

 

[Slowswinger]

Would this help? Third post down by Superchargeddrt
Flickering or pulstating Headlights