Wiring Questions

[Bingster]

I'm going through the wiring mess in my '47 Desoto engine compartment to get the engine started  and while it's obvious where they spliced in new wire, one has me baffled. The wiring diagram shows a green wire running from the coil negative terminal through the firewall harness and onto the ignition switch.

But the wire I have is an original looking yellow/brown kind of color, and it does go through the firewall wiring harness.  The other question is what does the wiring harness covering look like from the factory?  This harness is wrapped in a very heavy electrical tape.  It looks professionally wrapped, not done by a novice.

[knuckleharley]

First question,is the wiring you are asking about covered with plastic or cloth under the tape?

[DonaldSmith]

The original wiring was wrapped in black tape.  Not sure that it was adhesive.  Might have been tied at the ends.  

(Edit:)  I used cheap electrical tape for rewiring, but the heat or something made the adhesive gummy.  Maybe there is a high-temp electrical tape that won't deteriorate. 

 

Edited July 24, 2017 by DonaldSmith
additional info

[Bingster]

The original wire covering in my car is clothe covered with the tracer colors as well.

Also, I'm trying to figure out from the diagram and the Autolite starter solenoid on the starter, which way I am supposed to be looking at the four terminal posts. Is the huge post for the negative battery cable? 

If that's so, then to the right of that is another large terminal smaller than the other, with a metal tag attached to it.

[Bobacuda]

The black tape on my B4B was adhesive.   After I disconnected the line in each harness, I labeled where the line came from.  When in doubt at the other end, I used an ohm-meter to determine where the line went, then I labeled that end as well.  Once all of the wires were labeled, I removed that section of the wiring harness.  When I built the new section, I cut and peeled the tape back to see the color coding on the wire.

So, you can ring it out with an ohm-meter or you can strip back the tape to confirm the color.  WARING - the old wire's insulation will fall apart readily as you expose it.

 

[knuckleharley]

10 minutes ago, DonaldSmith said:

The original wiring was wrapped in black tape.  Not sure that it was adhesive.  Might have been tied at the ends.  

(Edit:)  I used cheap electrical tape for rewiring, but the heat or something made the adhesive gummy.  Maybe there is a high-temp electrical tape that won't deteriorate. 

 

No,the original wiring in your car is covered with either a cloth or a plastic wrapping,and THAT was what you covered with black electrical tape. It also will have straight lines of different colors running the full length of it so technicians can look at it and identify which circuit it goes to on the other side of the firewall.

This is important because the wiring on these old 6 volt cars is a lot thicker than the wiring on modern cars,and if you use modern wiring of a lesser gauge to connect to the original wiring,it can get really hot. Sometimes hot enough to catch fire,but often hot enough to become brittle and resistant to passing current.

[Don Coatney]

Are you going to believe the 70+ year wiring color that may have changed color over the past 70+ years? Are you going to follow the factory wiring diagram that some one may have not followed and altered in the past 70+  years?  Or are you going to do a hand over hand tracing to discover where each wire is connected and compare that to the factory schematic? What do you think is the best way to proceed?  I really don't think anyone here can correctly answer your question.

[desoto1939]

ON my 39 Desoto the OEM wire was cloth covered and the individual wires were in a braded covering that had blue stikes. The covering over the entire wire harness was black witht he blue strikers.

Does you coil mount to the firewal or is it mounted to a braket on the engine. My ignition has the coil mounted onthe wirewall and the ignition wire screws into the back of the coil and another wire is bolted onto the coil and goes to the breaker plate.  The original cloth covered wire was colored with specific strikers to indicate the gage of the wire.  The new cloth covered wire is modern wire with the plastic cover and then the cloth cover is pulled over the plastic. This make for a better protested wire so that grease and mositure does not get into the newer wire.

 

Rich Hartung

desoto1939@aol.com

[knuckleharley]

7 minutes ago, Bingster said:

Quote

The original wire covering in my car is clothe covered with the tracer colors as well.

Ok,now we are getting  somewhere. Am I correct in assuming you have not cut any away or made any additions using modern plastic-covered wiring?

Quote

Also, I'm trying to figure out from the diagram and the Autolite starter solenoid on the starter, which way I am supposed to be looking at the four terminal posts. Is the huge post for the negative battery cable? 

No. In these old 6 volt positive ground cars,the big post (which is the positive post) is where the positive battery cable goes.

 

 

[Bingster]

Thanks. I am taking each wire one by one and trying to trace it to where it belongs.  I cut back on the tape stuff to get to some fresh color on the wires. That helps. I'm temporarily replacing it with wire the same gauge.  I just want the wires necessary to start the engine. I've bundled and eliminated the light wires.  Any good photos of how the harness was attached and branched out?  I see the clips but sadly didn't take enough photos when I removed the stuff. 

[Don Coatney]

Hot wire it. To start the engine I use a short alligator clipped wire from the hot battery post to the coil and a home made remote starter button under the hood connected to the hot side of the battery and to the small post on the starter solenoid. You don't need to use any other wires. If the engine starts you remove the alligator clipped wire to shut it off.

[Bingster]

Mmmm. That would save me a lot of time. I remember when you posted that switch set-up awhile back. I forgot about it. Thanks.