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46 to 48 Plymouth wiring diagram differance


Ernie Baily

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I'm following the 46 wiring diagram when I'm doing some wiring repair on my 48 Plymouth which has some of the orignial wiring and the wiring is slightly different than the diagram. Has anyone seen a revised 48 Plymouth diagram printed? I'll make do with the 46 Diagram, but was just wondering.

 

Thanks,

Ernie Baily

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I'd be interested to know what differences you have found.  I have noticed some color differences between the chart and my 46, but I'm not always sure what the color really is, because it's so faded.  But now in the last week or so I have unwrapped the entire harness, preparing to build a new one, so I can now be sure of the original colors.  In some places a previous owner had painted the ends of the wires, so they could tell which was which, I suppose.  (I had repaired it all myself back in 80 or 81, and rewrapped the entire main harness with plastic electrical tape, but now the wire coating is really stiff, and breaks if you bend it.)  (The original tape used was the cloth type electrical tape.)

 

EDIT:

I have been looking at this a bit just now, and the major difference is that my car only has a single terminal block, not two, as shown in the wiring diagram in my manual (There are no other mounting holes in the radiator side shield, either, although there is a 'dimple' directly below the lower mounting hole for the 3 terminal block, at about the right spacing for a longer, 5 terminal block.  The hole does not go through.)  

Two of the three wires at that terminal block go to the dimmer switch, the other going to the dash, probably the headlight switch.

Orange, or possibly yellow , no slash marks (10 gauge?).  (I had that on the bottom terminal.)

Green, 2 slash marks (14 gauge?). (I had on the middle terminal.)

Yellow, 1 slash mark, (16 gauge?). (Top terminal.)

 

So I'm guessing that the 'fender lights' wiring was connected along with the headlight wires, to turn them on anytime the headlights were on.  I will need to add a longer terminal block in order to convert the fender lights into turn signals.

 

I think that the wires were not on the 'correct' terminals, according to the wiring diagram.  My car had the front clip off already when I got it, and I derusted and painted all of those sheet metal parts with everything dismantled, and I don't recall if we had any wiring diagram to look at back then, either.

 

Edited by Eneto-55
adding later comment
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Hello,  I may have jumped the gun on the wiring. I have two wrapped looms going into the body from the engine compartment. The two wires coming off the brake light switch going into one of the looms going into the body were real bad and not making conection. There was one wire coming out of the one loom going to another wrapped group of wire going to the horn relay. I used a jumper to go from the hot side of the brake light switch and low and behold the brake light worked. So I decided to unwrap  the loom and find the two wires that go to the brake light switch and they were Red as the diagram said. So I replaced both red wires with new red wires and the brake light works. So all is well as I did some other wire replacing under the dash in a hope to lessen the chance for a electrical fire.

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I had repaired the main harness back in 80 or 81, splicing in cloth-covered wire we stripped out of other old cars.  But recently I had to move some of the wiring that goes over the left side, against the roof, basically, and I realized it is extremely brittle.  So I decided to replace all of it.  But now that I have unwrapped the entire main harness, I see that the parts of the wire that were inside the wrapping are really in very decent shape.  So wondering about some options, for saving some money on this deal.  I guess it makes sense that those wires would get cooked up there close to the roof.

First deal about the original wiring is that I had seen a few places where I could see that it was tinned copper.  So I had the idea that all of it is.  (I think I also read that someplace, but don't remember where now.)  Anyway, very little of it is actually tinned wire, so I no longer feel so much push to get marine or military grade wire.

So I have some pretty good sections of wire that probably could be re-used, but for the most part, that would involve splicing, and I wanted to get away from that - just more places to have a short develop later, or a stiff or bulky place in the harness.  If I were to consider doing that, I would want to look for some sort of shellac to recoat it all, thinking that that might protect it from moisture, etc.

I've been looking at the different wiring diagrams in the manuals, and since the ones for the P15 and earlier models do not have the wire gauges marked, I've been comparing that one to the later ones, assuming that the gauges used were the same.  But there's some weird stuff going on with that.  Like in the diagram for the P19 & P20, the headlight harnesses have two wires, a Red 12 gauge, and a Black 14 gauge.  (Makes sense that the high beam would require a heavier wire.)  And, in that wiring diagram, it shows the same gauges for the wires that go into the main wiring harness, after the terminal block.  That makes sense, too.  Would seem that if you need heavier wire at the headlight harness, you need the same as it continues on.)  But the actual case on my 46 is different.

 

First, I should quote Ed (OldMopar) about how to determine the wire gauge.  I think I've read the same thing someplace else, because I had it in my notes as follows:

GAUGE    # TRACERS

18                    NONE
16                        1
14                        2
12                        3
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

10                    NONE
8                         1

 

Here's what I found on the site today:

TOPIC: D-24 Rewire

Post # 6

 

So the source is not an old MoPar manual, but Rhode Island Wiring.  Does anyone know for sure that this is correct? (like from a MoPar manual source)

 

But here's what I found in my actual case:

On the headlight harnesses (I have them for both the 46 & the 49 1st series, and they are identical):

Orange    2 tracers    (14 gauge?)
Black        1 tracer     (16 gauge?)
(or maybe Green?  I cannot tell for sure.  But the P19 diagram has Red & Black.  The P15 diagram does not label the colors for the headlight harnesses, only after the terminal block.  So maybe what I see as Orange is really Red.)  So according to the tracer to gauge chart, those wires are Orange (Red?) 14 gauge, and Black (Green?) 16 gauge.
(Then there is a short third wire inside the headlight bucket, which is Yellow, 2 tracers.)

 

But the weird thing is that the headlight wires in the main harness are different. 

Orange, Red, or Yellow (I can't tell)    No Tracer - This is the heavier one, so according to the chart, it would be 10 gauge.
Green (maybe Black, but sure looks green to me)        2 tracers - So this one would be 14 gauge.

 

I don't know if any of this makes sense to you, or if it is of the slightest interest, or if you even have time to read it.  But I'm puzzled about this, and would appreciate any clarification anyone can offer.

 

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11 hours ago, Ernie Baily said:

.... I have two wrapped looms going into the body from the engine compartment.  ....

I just have a single wiring harness on my 46.  It was built in Evansville.  Where was yours built?  (Wondering if the different factories did it differently.)

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Front running lites as stock should be OFF with head lights ON.  Running lights on with headlights on started 62 or 63.  To make the front parking lights function as park and turn indicators swap the single terminal pig tail for a double one and use twin filament bulbs. Wire signal leads to the bright element wire.  Same for rear if you want brakes and or signals at the rear also.

5011906_dcd_85801_pri_larg.jpg

Edited by greg g
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My Service Manual covers 46-53, i.e. printed at least 1953.

I add scans of wiring P-15 (1946-48) and P17-18 (1949) to show differences.

 

My scans are much sharper than here. If You want the filkes, please mail me

fleiter[at]t-online.de

 

Greetings from Düsseldorf!

Go

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PL_246A20-s w.jpg

PL_248A1 s w.jpg

Edited by Go Fleiter
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I found a site that describes how to calculate wire gauge for stranded wire.

Wire Gauge Reference Table

It's a bit of a complicated process, and accuracy can vary a good bit, because you start with the diameter of a single strand.  But according to this calculation table, a 19 strand wire with a single strike comes out closest to 16 gauge.  The wire tested is the smaller of the two wires in the headlight harness.

The diameter of a single strand of the heavier wire comes out very close to the same, but it has 26 strands.  It's a Red or Orange double strike wire, and that comes out to 14 AWG.  

These calculations match the information provided to Ed by Rhode Island Wiring, but these gauges do not match the wiring diagrams for any of the Plymouth models P15 - P20.

 

[I also tested a third wire, one of the wires from the heater motor.  The wire coating is way too deteriorated to be able to tell the color or the number of tracers.  It is tinned copper - this is apparently where I got the idea that the whole wiring harness was tinned copper.  The diameter of a single strand of that 19 strand cable is a bit more than the other 19 strand (single tracer) wire, but that is to be expected, due to the tin plating.  So it is also 16 AWG.]

 

Regarding the discrepancies between the headlight harnesses (on my two P15s, one a 46 from Evansville, and the other a 49 from Detroit) and the wiring diagrams (and also between the headlight harnesses and the headlight service wires in the main harness from my 46), I have no idea as to how to explain this.  Of course the P15 diagrams (and all earlier models for which I have the diagrams, back to 1936), so I was just assuming that the wire gauges used stayed the same into the P17 and following models, but this doesn't appear to be the case.  (I only have wiring diagrams for up to the P20.)  If it were only a single car, it might be easily explained by assuming that some later models used smaller gauge wire, and that this cabling was replaced at some time during the life of the car.  But not with two cars showing the same differences.

 

(This may all seem like an idle pursuit, but I want to use adequate size wiring when I rebuild the harness.  I realize that various people have suggested just using larger size wire throughout the vehicle, but if I'm already going to add a lot of extra wires to the harness, then the hole where it passes through the firewall is going to get mighty tight.)

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  • 2 months later...

More about wire gauges, and a question about what seems to be a discrepancy to me.  (Need an electrician's input.)

 

Because most of my wiring is so badly aged that I can hardly see any strikes, or what color it was originally, I've been counting strands, and comparing the different wires, in order to confirm the correct gauges for each run, and also to make sure that the wire I buy will not be such course strands that it is too stiff to make it go where it needs to.

 

Here's what I've found (adding to what was previously posted by others re: the number of strikers for each gauge):

 

AWG          # STRANDS          # STRIKERS (slashes)

 16                       19                           1

 14                       26                           2

 12                       41                           3

 10                       65                           0

 

Here's the question:  As I mentioned in a previous post, the head light sub-harnesses (the individual separate ones that go from the terminal block to the head light buckets) on both my 46 and my 49 (1st series) have smaller gauge wires than the main harness.  For instance, the main harness high beam wire is 12 AWG (41 strands), while the high beam wire in the front harness is only 14 AWG (26 strands).  Why would they have done that?  Has anyone else compared the wire gauges used for the head light harness as opposed to the main harness?  (The low beam wires are also 1 gauge smaller on the front sub-harness.)  If I only had the front sub-harnesses from a single vehicle I could easily think that these harnesses had been replaced with something from an earlier or later model, but the odds that this would have been done on both harnesses on both cars are pretty slim.

 

One last comment here (unless I think of something else yet...? As everyone knows, the P15 wire diagram does not note the gauge for each wire.  The diagram for the P19 - P20 shows the wire gauge separately for the headlight front sub-harness, showing 12 AWG for high beam, and 14 for low beam - the same gauges as shown for the main harness, and also the same as I found to be the case on my P15 main harness.  

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