1972 Plymouth scamp charging and grounding issue
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
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.
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
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.