1972 Plymouth scamp charging and grounding issue

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1972Plymouth

1972Plymouth

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I have a 1972 Plymouth scamp with a 68-69 dodge 318, I freaking love driving the car. But I've been beating my head against a wall trying to figure this issue out. So I figured Id ask my other fellow A body mopar people for some advice and help. 3 weeks ago my battery died, along with the original lead terminal ends, so I replaced them and continued on my way. Then two weeks ago my alternator went out, that's when the problem started. I replaced the alternator and voltage regulator, but its still having the same issue. Its starts and idols just fine, and drives pretty smoothly, although rough at times. But the alternator gauge has it with -40 to +40, when I start it the gauge is dead center like it should be. But when ever I press on the brakes in drops a little to the left towards the negative side, when the blinkers are on it bounces from left to dead center. And if you turn on the lights it drops to 5 points above -40, and has a hard time running. I know its a grounding issue, so I cleaned where the battery grounds to the block, and replaced the secondary starter relay. That worked for about 15 minutes and then it lost power 3 times while driving, but starts right up again when your start it. The third time it did the o noticed the gauge was all the way to -40, so I limped it home, the light issue is back again. I know something is not grounding right and causing resistance to the charging system. I'm not sure what else could be the problem, so id like to know if any of you guys have had similar experiences with that issue. I would greatly appreciate some advice. Thank you 1972Plymouth
 
Do you have all of the necessary chassis grounds in place. Not sure that's the issue, but it's a good place to start.
 
Its got a ground from the block the body, not sure if I should add another or if there is a hidden one down by the starter.
 
It has one from the block to the body, but I'm not sure if there is a hidden one down by the starter
 
Should have, well at least mine has, a ground from battery negative to core support and driver side head. It has the braided strap from passenger head to firewall.
 
Yea mine has a ground from the negative battery cable to the drives side block and a braided ground from the back of the black to the passenger side firewall.
 
i had this issue in my scamp, given it was with a slant, but i replaced the whole charging system and it still had the issue. i found that some of the older ground wires while connected had some corrosion in the middle of the wires (found it after i replaced them and cut them in half to check) short story long i found it easiest to replace all the ground wires at the same time just to be safe. fixed the problem right up. the wires may look fine on the outside but have corrosion inside, something to keep in mind.
 
I replaced the one from the battery to the block, but ill see about replacing the ground from the block the the body. And any other grounding cable.
 
This may NOT be a ground issue

If you don't have a factory service manual, you can download them here

http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617

and more manuals and more info here

http://www.mymopar.com/index.php?pid=31

The IMPORTANT thing to do is read this article:

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Even if you do not perform "the bypass" this article points up where problems can occur. Pay attention to the diagram on that page, reposted below:

This is a simplified diagram of the primary power distribution. The "important points" (follow along on the diagram)

From the battery, down to the starter relay, the first point of suspect is the FUSIBLE LINK. From there we follow the red wire into the terminal passing through the BULKHEAD connector. Continue on to the AMMETER connection, THROUGH the AMMETER, and the BLACK ammeter terminal. Continuing up we have the WELDED SPLICE, back out the BULKHEAD CONNECTOR, and to the ALTERNATOR

All of the above BOLD points are points of failure, the bulkhead terminals, the terminals on the ammeter (and the wire ends themselves) inside the ammeter, back out the bulkhead, and the terminal itself at the alternator. In rare cases, the "welded splice" has and does fail. This is a splice in the black ammeter wire up under the cluster in the harness, a few inches from the black ammeter termination.

NOT shown is MORE trouble. From the WELDED SPLICE we tap off and feed the IGNITION SWITCH CONNECTOR, THROUGH the SWITCH, back out the SWITCH CONNECTOR (on the blue ignition wire) and back out the BULKHEAD connector to feed the ignition and charging system under the hood

So this is several more points of failure, involving connectors and switches, and yet one more suspect terminal in the bulkhead connector

amp-ga18.jpg


HOW do you find this?

Search here for some of my posts on voltage drop.

Wiggle the wiring and bulkhead connector. Snap the connector apart, inspect, clean, replace, bypass, fix, the connector

Take a multimeter and make some voltage tests. We can step you through that. It can get a bit involved, but if you take it "one step at a time" it's fairly easy.

Start with the easy stuff first, the things you can reach.

You can reach the engine side of the bulkhead connector

You can reach the ignition switch connector under the column.

You 'might' be able to access the ammeter later on, by disconnecting the battery and reaching up under the dash.

So far as grounds, "these are" the minimums

You need to have the main battery NEG hooked to the engine block. You need at least one GOOD ground either from the battery to the body or from the engine to the body. This could be parallel no 10 wires of at least 3, or could be a "starter" "eyelet to eyelet" type cable you can buy at any parts store.

On a V8, look at the alternator mount. These same bolt holes in the end of the head are on the BACK of the driver side head. Fasten a short no4 starter cable there with a short bolt, and either bolt to the firewall, or a good place is one of the master cylinder studs.
 
Mmmmm, OP , seriously sounds like your new alternator and/or voltage regulator are not working and the alternator is not putting out any charge. The left-of-center readings on the ammeter all point to the alternator not putting out any charge.

Does the ammeter deflect to the right of center at all if you increase the engine speed from idle to fast idle with nothing turned on? It should show some right-of center- deflection; the more discharged is the battery, the more there will be right-of-center deflection.

Get access to or buy a voltmeter. It will be your friend on this car! Check the voltage across the battery at fast idle and warmed up, it should measure in the range of 13.7 to 14.3 volts. If it is much lower, then the alteranator is not charging. If you do this, please report back with the voltage that you do measure across the battery at fast idle.

BTW, a bad ground of the voltage regulator case to the chassis will cause the alternator to not charge so check that while you check all else in the grounding of the system.
 
But it only happens when the lights are on, if they are off then its dead center. Could it be the lights causing resistance somewhere or is it something else? The battery is 12.68 when idling and 12.93 when brought up to 1700 rpm.
 
I'd advise to read up on some of 69darts's posts. He has helped out myself and a bunch of other members on electrical issues. My first place to check would be the bulkhead connectors.
You need to start checking for voltage drop.
 
1972Plymouth said:
But it only happens when the lights are on, if they are off then its dead center. Could it be the lights causing resistance somewhere or is it something else? The battery is 12.68 when idling and 12.93 when brought up to 1700 rpm.
Click to expand...

That's why it sounds to me like a connection issue in the harness rather than a ground

Of course you could have 2 or more problems.
 
First things I'd try

1.......As others have also suggested, inspect and retighten grounds from battery to engine, to body, etc

2.....Dismount the voltage regulator. Scrape the mounting and firewall clean around the bolts and re-mount using star lock washers. It MUST be tight and grounded. Do the same with your electronic ignition

3.....To get a "start" on looking for voltage drop, and because this is intermittent, try this one thing. Make up a good heavy clip lead, say, at least no14 or better no 12 wire. Turn the key to "run." Probe the ignition ballast to find the highest reading. This is the "key side" of the ballast. Get an adapter spade connector if necesary. I can't find a photo, similar to this:


41KULbaDzML._SX300_.jpg


With the car started and running, and your adapter in place on the ballast, hook your jumper wire from there to a battery source, such as the big stud on the start relay. This effectively hot wires the car, and guarantees a solid battery connection to the ignition buss.

See if that settles down the charging problem
 
1972Plymouth said:
But it only happens when the lights are on, if they are off then its dead center. Could it be the lights causing resistance somewhere or is it something else? The battery is 12.68 when idling and 12.93 when brought up to 1700 rpm.
Click to expand...
Those ammeter and voltmeter readings are normal for an alternator not putting out properly; understand that the ammeter indcates current going into and out of the battery. The left-of-center (- or Discharge) readings when the lights are on indicates a drain of current out of the battery rather than it coming from the alternator as the light's current should. That might happen at low idle but should NOT happen at fast idle. The lack of right-of-center (+ or Charge) indications without an electrical load says that the battery is not being charged. You should see + or C readings after starting the car, staying that way for a while until the battery is well charged.

The voltage readings you show confirm this. You ought to have more than 12.7v at the battery at low idle, and in the range of 13.7 to 14.3 v at fast idle.

Important question: Did you get the alternator for a 1972 Scamp? That should work right with the same year of VR, but a 68 318 alternator won't work with a 72 Scamp VR. So we all need to know what years of VR and alternator you have. To be right for 1972, the alternator will have 2 small field wire connections on the back (in addition to the large output lug).

If this is the case, then remove the green field wire from the back of the alternator and ground that connection on the alternator (not the wire). This should jump the voltage at the battery up to 15 volts or higher. (Do this only long enough for the test.) If this works, then the alternator is OK and the VR or its wiring are the problem area.

If you replaced the voltage regulator (VR), then it can be bad out of the box. I just went through this with a guy over on the FBBO forum; a lot of tests he ran (like above) showed the circuits to be properly connected and normal. He had replaced the VR twice but still had low charging voltage like you have. He put in a new Wells VR and 'presto', it was all good.
 
1972Plymouth said:
But it only happens when the lights are on, if they are off then its dead center. Could it be the lights causing resistance somewhere or is it something else? The battery is 12.68 when idling and 12.93 when brought up to 1700 rpm.
Click to expand...

It's a common problem with these old girls, I can't tell ya how many I have owned over the last 40 years that do what you're describing.

I always started by checking all of the grounds, check the alt. belt to make sure it's adjusted up properly and not slipping under load.

From there it takes more looking into.
 
nm9stheham said:
Important question: Did you get the alternator for a 1972 Scamp? That should work right with the same year of VR, but a 68 318 alternator won't work with a 72 Scamp VR. So we all need to know what years of VR and alternator you have. To be right for 1972, the alternator will have 2 small field wire connections on the back (in addition to the large output lug)..
Click to expand...

This is true but it "gets worse."

It is common for the backyard rebuilders to MODIFY the older cases and add a brush, and it is somewhat common for the 'proper' alternator to have hardware or defective hardware which INCORRECTLY causes one brush to be grounded.

The short answer is "you need a squareback" alternator, AND you need to electrically check that neither brush (field) is grounded to the case

Below is an improper 69 / earlier case which HAD been modified by a rebuilder to install an insulated brush at 12 o'clock. This "converts" the unit into a 70 / later unit. One problem with this is that the brushes used don't fit properly, and the second is that someone can install a grounding (original) brush which won't be good in a 70 / later installation

128306-500-0.jpg


Below is an interesting situation. On the left is a roundback, I've never seen one. This appears to be factory, and appears to accept EITHER a grounded or insulated brush. The one YOU WANT is on the right, a "squareback". These are superior in design, put out better at low RPM, and "only come" in isolated brush, "what you need."

squareroundcomp.jpg
 
My old alternator and the new alternator are both squareback ones, like the one on the right in the picture above
 
OK, very good to know that; 67Dart273's pix are worht a thousand words.

Do the test outlined in post #18 and see if the voltage output at the battery jumps up. I bet it will; the fact that you are getting a tiny bit of charging from the new alternator (as evidenced by the 12.93v output at fast idle) says that part of the alternator is good (stator and at least some diodes), and that test will confirm or deny that the rest of the alternator (the other diodes and the field and brushes) is good too.
 
Well the alternator was the problem, it was shorting itself out internally. So I had it replaced, bench tested the new one, and it passed. It was 13.7v low and 15.6v as the high, it worked for about an hour. And then the problem came back.
 
What do mean by bench tested? Test at a store on a machine or??

Can you descrtibe how it was determined that it was shorted out intenrally?

Where are these alternators coming from?

Is the 13.7v low to 15.6v high in the car? If so , is the low idle and fast idle, or under what circumstances?
 
nm9stheham said:
What do mean by bench tested? Test at a store on a machine or??

Can you descrtibe how it was determined that it was shorted out intenrally?

Where are these alternators coming from?

Is the 13.7v low to 15.6v high in the car? If so , is the low idle and fast idle, or under what circumstances?
Click to expand...

This is a common problem, as I detailed above. Cheap, third world, sloppy "rebuilders"

Well, ya learned something I hope, LOL

Ya got 'er workin
 
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