Low Body Voltage
1962 to 1978
There are quite a
few places this can happen. Itís all in the connectors and quality of
the remaining wiring. This will be sort of generic, there is a breaking
point in production concepts of some of the cars, but when I am done here, I
think youíll see what I mean.
Low Body voltage
is a problem. It tends to degrade connectors and wire because of over
heating. But! If you see burned insulation on wires, near a connector,
you have found one of your problem spots. This is also true for shorts,
which burn wires.
Letís list the
tools you need. Besides the obvious screw drivers and pliers needed to
access the wiring locations, it would be a good idea to have a test
light, volt meter, soldering gun and Flux Core solder. Donít forget a drop light
or flash light.
If you know you
are going to be working on a power feed problem, get some #10 wire. It
can be purchased in different colors and in 10- foot lengths. I suggest
Red and Black and 25í packages. Invest in some shrink-wrap for the
wiring as well. 3/8í is good for #10. Shrink-wrap, while expensive, has great insulation properties, and will give you a much
neater job when done. Get some shielded solder-less connectors and butt
connectors. You want both male and female spade connectors in the
YELLOW jacket for #10 wire. Blue for 12 to 18 Ga. Try to buy the ones with the plastic shield around the
spades as they will be safer and save you time shielding them.
Electrical tape has a tendency of pealing back.
If you are new to
auto electrics, I suggest you read this link first:
Basic Wiring Tips Click here
Get your tools and
supplies together before you dive into this
So letís review
A. Lights are dimming
B. Ammeter is either
over charging or under charging
C. Nothing works
D. Discharges as you
99% of the time,
all of these symptoms is as a result of poor connections. Keep in mind;
you may have damaged other connections on accessories. This is common
OK so letís assume
you have eliminated the obvious . . .Bad Battery, Bad Alternator, wiring
under hood is in tact.
Hereís what to
- Check the
pigtail connection on your battery. If you have a replacement
connector, make sure itís tight and clean. NO CORROSION! Make sure
you have good connections in the battery connector. If in doubt,
re-strip the wires and replace the connector,
- Follow the
pigtail to the fusible link connector. Take it apart and be sure
the connector isnít burned and is tight. If not, it will need to be
- Now look at
the fusible link itself. Run your fingers down it and feel for
knots or lumps. The knots or lumps usually mean there is corrosion
and should also be replaced. Please note, some cars do not have a
link in there. The link could be at the bulkhead connector or none
at all. (Early 60ís) It is a good idea you replace the link
anyway. They tend to degrade over the years and leak voltage or
could disintegrate without notice.
- Check the
connector at the other end of the link. Inspect it for tightness,
corrosion, or burning. If any of this is present, this too needs to
- Continue to
follow the heavy wire to the bulkhead connector. This is where it
gets interesting. All of what you have looked at so far is very
important. This is where the engine compartment feeds the car and
all itís accessories.
Please note: The images
provided below mostly came from the same harness. The
exception is the image with the fusible link on the bulk head
connector. These will show you what can happen if you leave a
low voltage problem unattended too long.
Here the link has been repaired where the quick connector was
probably burned. The mechanic did the right thing by crimping
and soldering. But the link has developed corrosion at the
repair point. Usually Links are degraded when this is scene.
This particular situation was a result of over heating and using
acid core solder.
This is from a 70 Plymouth. The red circles indicate over
heating on this harness where the fusible link is fed from the
Disconnect the battery
the plugs from the bulkhead connector. They are keyed, so you
canít put them back in the wrong places.
No apparent Damage here
- Look at
the spade connectors in the plugs. Look for corrosion, or
melted plastic. Particularly around the bigger wires. The
Bigger wires are the main power feeds for the charging system
and body feeds. If you see browned, corroded plastic or wire
insulation, this is a place you need to pay some attention and
probably cause for your problems. However, I remind you, any
poor connection in this primary circuit is critical. Letting it
go will only make it worse in time. You also leave an
opportunity for components to fail prematurely.
- Now the
fun part. Under the dash, On the C bodies, the bulkhead
connector is behind the fuse block. May be the same on the
early 60ís, but youíll know when you are under there. Here
again you need to inspect all your connections on the back side
of the connector.
Here an accessory wire
has been burned by an over load. This happens to be the
feed to the heater blower.
Heater Connector. I would examine your blower switch too.
Earlier 62 to 69 (Maybe 70) the
Ammeters were used in the primary circuit. The whole load ran through
the ammeter. The power went in one end, registered on the meter, and
cam out the other end, feeding everything, including the battery. From
70 on up, the cars had a parallel
circuits. One circuit ran from the alternator back to the battery. The
ammeter was piggy backed on that with a shunt. The ammeter was not
used as a primary supply device, but showed the usage of current without
being in the line directly. (Did that make sense?) Well anyway, the
whole car didnít run through the ammeter. The battery circuit ran into
the body through a separate wire, (The one with the fusible link) which
fed the ignition switch and accessories.
- So far,
weíve covered half the trouble spots. On the cars with the
Column ignition switch, the connector
is at the bottom of the column. The tilt column has the whole switch at
the bottom of the column. This is better as it eliminates a bunch of
wire and a connection block. These are trouble spots also. Most are
white plastic, so it will be easy to see damaged wiring or connections.
Like the bulk head connector, look for burned plastic, connections or
insulation. These hot spots will cause resistance and only continue to
This is a column ignition switch
connector. Located under the dash next to the steering column.
The red wire is the primary ignition feed. Obviously the damage is
pretty bad. This is from the same harness as the burned heater
connector (Above) and damaged fuse box.
- On dash
ignition switches, the connections are on the back of the
switch. You need to remove the switch and examine the
connections and wiring. These connections are held on with
nuts. The nuts tend to loosen in time and again may cause hot
spots. Examine these connections and wiring as before. If
possible, I suggest you replace the ignition switch while
there. This way, you are sure there is no internal damage
causing high resistance.
ammeter is another story. As mentioned, the earlier Mopar
vehicles used the Ammeter in the primary circuit. The car was
dependant on the meter and the connections on the back. Here
again, you will have to remove the meter from the dash, or pull
the cluster to check the connections. This is usually another
trouble spot. Some people bypass the meter by putting the two
wires on one terminal. However, if the connections are burned
and there is burned insulation, you need to replace the
connections. Before doing that.
More to come Don't wait for me!