It's 40 years old, perhaps it needs to be rewired.

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My 1967 Dodge D100 pick-up has been plagued with electrical problems
since
last summer. It started with a strange smell (I found out later was
the
AMP meter burning)
CY: Oops! That's not good.

that would last for about 10 minutes every other day 2
or 3 weeks before the electrical system completely shut down without
warning usually while sitting at a light.
CY: Burning smell, then shuts down....

After letting it sit for a while
(maybe 10 min. to 2 hours) it would start up and run for 5 minutes to
5
hours. If I started it in the morning and ran to 7-11 it will not
start
for at least 10 minutes and maybe 1 hour. When I turn the key
absolutely
nothing happens. No accessories work including lights and bypassing
the
starter relay will allow the starter to turn over but no spark to run
the
engine.
CY: That sounds familiar. My parents had an old Imperial LeBaron that
did that. Had the totally huge V-8 engine in it.

While it is running it charges the battery. I change the starter
relay, voltage regulator & resister block but nothing changes. After
noticing the AMP meter is on fire one day I tear it out and seems to
fix
the problem but it starts dieing again the next day. I change the
ignition
switch and notice that when I play with the head light switch and turn
the
key in the ignition at the same time something catches and it starts
up.
CY: My guess is coincidence.

I drive it like this for a week and then change the headlight switch
and put
in a new AMP meter. This fixes most of the problem, the truck no
longer
dies and the alternator charges the battery.
CY: Good job!

The dash lights had never
worked since I bought the truck and now they work but blinkers, horn &
heater do not work. It runs like that for about 2 weeks until one day
all
the accessories shut down including all gauges (the things working are
the
head and tail lights, break lights and the low break warning light on
the
dash.) and the battery drains while running with lights on.
CY: Wow, that's no good.

By charging
the battery at night it can be driven during daylight hours. I change
the
alternator that Shuck's says is bad but does not fix anything and try
another battery. Then one day it would not start at all and the
battery
would drain even when just sitting overnight.
CY: I presume you tried leavign the battery cable unhooked at night?
That is the test to see if it's bad battery (dead in the morning) or
bad electrical (leaving the battery unhooked lets it start fine in the
morning).

I noticed that when I pulled
the headlight switch the parking lights (blinkers not blinking) would
come
on in the first position but in second position would go out when
headlights came on. I changed out the headlight switch again and
charged
up the battery and it started right up. I drove it 2 miles and turned
it
off. It would not start again and I bought a new battery. When I turn
the
key the engine starts running but dies as soon as I let the key go
back
and disengage the starter. Bypassing the starter relay makes the
starter
turn but no spark starts the engine. I changed the ignition switch but
still will not run. I have a wiring diagram and have started replacing
some wires with no luck. Still runs only while key is turned all the
way
to start position. All accessories and gauges do work now when the key
is
turned one notch or backwards. It is a slant 6, automatic with no
radio or
cigarette lighter. I have changed the battery, battery cables, starter
relay, AMP meter, ignition switch, voltage regulator, resister block,
alternator, headlight switch, wire from alternator to voltage
regulator
and all fuses. Does anyone have any ideas or should I put a bullet
through
the engine block?
CY: Instead of throwing more parts at it, you need a volt meter, and
someone who knows Chrysler wiring. One thing that did come to mind
(well, at least I'm not going to tell you to replace a part) is the
thin wires coming off the positive battery terminal. The problem the
Imperial had (and several of my Chryslers after that) is that the
bullet connector would corrode. the solution is to go to the battery,
find the black plus side. There will be one or more small wires from
the battery terminal. About six or eight inches from the battery,
there are white disconnects. Squeeze and pull, they come apart. Clean
em out good with tiny pieces of sand paper, tiny wire brush, or WD-40
and Q-tips. Get the terminals as clean as you can, and dope em with
grease or NoAlox (electricians anti-oxidant) when you put them back
together. Please let us know if this helps.

You definitely need a wiring diagram for the truck. Get the factory service
manual, which has more info than you can imagine.

Get a new wiring harness before you burn that truck to the ground. You might
check with the hot rod aftermarket companies for a generic harness if you
can't find a repop.

Budd

Back in those days the bulkhead connectors were a big headache. Decon the
battery and pull the bulkhead connector apart, separate the places where the
wires are burned and fused together, rewire as necessary. Check under the dash
in the area of the instruments and see if the pack rats have eaten thru the
wiring and caused shorts.

get rid of the amp meter.  you will most likely need to replace
firewall bulkhead connectors and factory fuse block as they are
corrodided/melted.

Link below shows how to bypass amp gauge on 70s Dodge trucks, should
work on yours.  I did this about 4 years ago to 2 79's and have had no
problems since.  Instead of fusable links you can use a slow blow
fuses.

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

get rid of the amp meter.  you will most likely need to replace
firewall bulkhead connectors and factory fuse block as they are
corrodided/melted.

Link below shows how to bypass amp gauge on 70s Dodge trucks, should
work on yours.  I did this about 4 years ago to 2 79's and have had no
problems since.  Instead of fusable links you can use a slow blow
fuses.

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

Start by finding a factory wiring diagram (better yet, a complete factory
service manual).  http://www.moparmanuals.com/ shows it available on CDROM
(#81-370-7350) for $65.  If you intend to keep the truck, this would be an
excellent investment.  If you don't intend to keep the truck, it adds a
selling point!

A vehicle this old likely has oxidized connections almost everywhere.
Disconnect & inspect every connection you can find.  While some advocate
eliminating the ammeter, it can be left in place IF it's not open-circuit
and the connections are clean & tight.  Connections thru the firewall are
also problematic, particularly the two that connect to the 12ga wires.  Even
the *slightest* poor connection in these will cause problems.  The dead
giveaway is the melted/distorted housings for these connections.

"Then one day it would not start at all and the battery would drain even
when just sitting overnight." The battery going dead on its own is
symptomatic of a separate problem... either a bad battery, or something not
switched by the ignition switch is draining it.  Check the specific gravity
of the electrolyte in the battery. Fully charged, all six cells should be
above about 1.25 and close to each other.  Terminal voltage should be above
about 12.5V.  If that looks good, connect the battery with a milliammeter in
series, and you should see zero current flowing -- a cheapo Radioshack VOM
will work.  If you have *any* current flowing, start disconnecting (usually
aftermarket or miswired OEM) items until you see zero load.

Bryan