[Chrysler300] Volta's revenge

["Rich Barber" <c300@xxxxxxx>]

Christopher and all:

Always interesting to read Christopher's missives from down under.  And,
just a note to remind those driving modern 300's (12-Volt, negative ground
newfangled electricals) that the vintage C-300 of 1955 did have a positive
"earth" or "ground" connection as we refer to it here in the USA.  All 1955
Chrysler products (other than the Crown Imperial) also had 6-Volt systems,
as did Ford products that year.

As I recall there was serious disagreement between Chrysler/Ford engineers
and GM engineers on which polarity was "best".  I think the basic issue was
the current flow at the spark plug tip.  The logic being that current flow
was better from the plug body to the tip, rather than vice-versa.  That
would erode the tip at a slower rate.  GM went to 12-Volt in 1955 and
Chrysler and ford switched in 1956.  The Chrysler Crown Imperial of 1955 had
a 12-Volt positive ground system.

As a grease monkey in the Midwest that year, I had to be very careful when
jump starting cars to make sure I had the correct polarity.  Incorrect
connection resulted in one heck of a flash.

I'm off to the car show.  Wish me luck.

I hope everyone has a chance to show off their 300 today and have a happy
Fourth!

God Bless America and God Save the Queen!

C-300'ly,
Rich Barber
Brentwood, CA

-----Original Message-----
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of christopher beilby
Sent: Friday, July 04, 2008 4:16 AM
To: Chrysler300@xxxxxxxxxxxxxxx
Subject: [Chrysler300] a cause of 300 wiring harness shorts/burnups?


As some have already said/hinted, in the 300C, there is indeed a heavy/thick
main power wire that passes through an open loop in the back of the dash
ammeter, which apparently was still much the same in some later year 300s,
according to other member's reply to the 'in car/300' wiring harness
meltdown suffered by a member recently.
 
I have had two instances in my 300Cs where the main wiring harness from the
engine bay to the dash cluster has self destructed - burnt up, and the
causes, although different, but the same, may provide help as to what
happened with our Member's 300 harness fire/short.
 
My first 300C instance where the main ammeter loop wire fried the harness
from power source to dash, was the ignition tumbler came apart internally as
I turned the key (I forget just how - I remember more it happened just after
I had painstakingly rebuilt the harness with exact correct color wires after
a previous owner had put in all black/wrong wires - like why couldn't the
lock fall apart 'just before' I rewired it !!!!!), and allowed the loose
power wire part of the ignition wire/terminal to touch the body/ground/dash
sheetmetal.
The second instance, this time in my driver 300C, was my stupidity (as
distinct from the earlier 'act of god' !), as I had left free the battery
vertical round anchor rod that usually goes onto to the battery hold down -
it fell backwards as charged over a rough rail line, and in another freak
(act of god, or act of Mopar - you decide ?!), it is the exact 100% perfect
length (yes the exact perfect to fractions of nothingness/inches) to not
only touch, but stay on the power terminal/lug of the voltage regulator, and
in effect provide a total dead short - which again somehow burns out the
heavy red wire that runs to/through the dash ammeter.
In both cases, the amount of white smoke is truly amazing/terrifying.  But
the good news is, if you are lucky/quick, and have left one battery end/lead
onto your battery just loose enough so if is secure enough to start, but if
twisted by hand, it comes up off the taper all battery posts have, then you
may have only burnt your ammeter heavy wire, and not ruined all the other
wires taped in harness with it?! 
 
Other similar 300 year owners may have had other 'wiring harness frying
events/visitations', but what I am suggesting is that the most common
'common element' cause of '300 wire frying harnesses' may be that somehow
there has been a power wire dead short to frame/body - whether that
can/occurs with a faulty alternator as some have juist suggested as cause, I
leave to those more 'electrically knowledgeable/inclined'.
 
In both my cases, by having a battery cable end free enough to wrench/twist
off, my battery was not flattened, and in the rail crossing incident case, I
hot wired the ignition coil from the nearby battery, and then used a
screwdriver to bridge the also nearby needed contacts to crank the engine,
and drove home - so if the battery is not flat in this latest later 300
case, maybe this also points to a frame/body dead short burning out the
harness through ammeter?
 
And a quick further final on this topic.
A friend of mine asked could I help him start a 68 Mustang that had been in
it's grave for maybe 20 years, asked if needed, if it didn;t fire straight
off, could I pump the carb as it not connected.  He then put a battery in
it, headed to the drivers door to crank it, and just as he did, huge clouds
of white smoke rose - I grabbed the lead off the battery, and saw the red
lead he had connected to usual positive/red battery terminal was in fact the
earth lead that usually goes to motor/negative, as he said 'did I do that -
what did I do !!!!?  Anyone who has put the leads arse about onto the
battery of a car with an alternator is going to be up for some bucks/$$$
redoing their harness, plus alternator will now not charge.  So here is
another trap to avoid - never use red color battery lead for any
earth/negative battery connection (always use black for negative lead), plus
always check any battery lead you are about to connect to negative of
battery that it indeed does go to earth/motor/frame if it a car you not
familar with - that is unless it is an early vintage car that has positive
earth, or a 50s/60s 'english', like my 58 Austin Healey, or early E Type
Jags - that have positive earth wiring systems.
 
More than enough said, sorry if I bored those who know/knew all this
already,
 
Christopher
ps happy 4th of July American Celebrations - here in Australia this time of
year, virtually no car events or much else on in winter, except footy
 
 
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