Do-it-yourself wiring

[steveplym]

I'm needing to replace the wiring in my P-15 and wanted to do it myself as I have plenty of wire, connectors, etc. Would be cheaper than buying a wiring kit from Rhode Island, etc. The wiring looks easy enough to replace by looking at the diagram in the manual. Wondering how many others have done this themselves and if there are any problems with replacing the wiring this way?

[Plymouthy Adams]

If you are rewiring stock it is simple and easy to repace your own harness...

[Normspeed]

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It's way cheaper to do it yourself. I've done my engine and overdrive harnesses and soon to do the headlight and body harnesses. Just use the correct wire sizes or even larger.

I tagged all the ends before disconnecting and removing. Held the tags on with little zip ties. The tags don't need to correctly say what the wire is such as regulator ground, as long as it describes where it was attached, like reg top, reg middle, etc.

Once tagged, I stretched the old harness out, removed the wrapping, and made up new wires one at a time, transferring each tag to the new wire with zip ties. Then back in with the new stuff. I used the split loom stuff to cover the wires. Wrapping with the proper wrap would look nicer.

[JIPJOBXX]

I replaced all the wiring up under the hood and all I did was think strait and replaced all the old wiring with new. Time consuming but it worked out great and I have had no problems.

[david lazarus]

I rewired my '38 without an old harness to folllow, it is dead easy....but you do have to plan, label, label and label everything! Buy lots of different coloured wires, cable ties etc. It also allows you to build in extras (radio, elect wipers,door operated courtesy light, trunk light etc. Also a must is a continuity tester as ground can be intermittent. I also made sure I left lots of extra wire at the end destination (light or whatever) easier to chop some off than to add on!!

If I can wire one of these it must be easy!

[Guest jjmorrse]

I rewired mine while writing a masters thesis on 19th century woodworking machines. It was really straightforward. I lived in an apartment at the time, and did it bit by bit. I added junction blocks at the firewall and trunk, which allowed me to do the engine compartment separate from the interior, and I used waterproof heatshrink crimp ends. I used the stock colors and replaced wire by wire as I had time. I have not had a connection failure yet. My advise is not worth as much as a lot of guys on this forum, but I would suggest that you either do it a little at a time like I did, or be sure to block out enough time to do it over a relatively short period of time. It can get a little tedius and start to look like a rats nest if it is not done methodically..

[teardrop puller]

I did mine by following the wiring in the manual. These old cars have very simple wiring and it is pretty easy, Scan the page of the wiring and use a copy of the page to trace when you install a wire. Try to come up with a color scheme that works. You can do it.

kai

[steveplym]

Thanks for the help all.

What gauge wire is most commonly used for this swap. 16-18ga?, or is that too small a size?

I plan on replacing it one section at a time. Want to pull out the dash anyway to repaint so will be a good time to do it.

[Norm's Coupe]

Actually, there are at least two different size gauge wires and maybe more in the diagram. If you have the shop manual it does not show the gauge used in the 46 - 48 Plymouth, just the wires. However, if you flip the page and go to the 49 Plymouth, it shows the gauge wires to use. So, go by the 49 diagram for the wire gauges.

[greg g]

If you are staying 6 volt you need beefy wires. 6V is current flow based so you need lots of strands to get the current where it wants to go. Rule of thumb is

Heavy loads (headlamps heaterblower, horns genny to regulator, etc) 10 gauge

Medium load (parking, signal Ignition circuit ) 12 gauge

Light load (dash lights) etc 14 gauge.

Nothing lighter tha 14 should be used for 6V

[Norm's Coupe]

Greg, while using heavier gauge on the wiring won't hurt anything. However, I just replaced the wiring from the dash to the fuel sending unit in the trunk. Checked the 6 volt wiring diagram in the manual and that is only 16 gauge wire. So, you can use some lighter gauge wires in some areas. Just depends on what the circuit is for.

[Young Ed]

Norm I just thought of something there too. The gas gauge works with the sender on resistance right? So wouldn't that actually be one place where heavier wire could cause an issue?

[Norm's Coupe]

Norm I just thought of something there too. The gas gauge works with the sender on resistance right? So wouldn't that actually be one place where heavier wire could cause an issue?

Ed, I'm no expert but I think you might be right since the gauge works off heat. If it takes longer to heat up the wires, it could cause an inaccurate reading on the gauge. Again, I'm no expert, but it makes sense to me. The bigger the wire the longer it takes to warm up, or it could cause the wires to transfer more heat and still give you a wrong reading. I'm also using 16 gauge on the 6 volt LED extra stop and turn signals I installed and they work fine too. I didn't check the size of the horn wire, but I did have one out of an extra steering column. That wire looked like either 16 or 18 gauge too going by sight alone.

Even if we're all wet in our thinking, there's still the cost factor. The heavier the wire, the more it cost. If you have the manual giving the correct size, why go heavier than what's needed. Plus when using lighter gauge wire, it's easier to work with.

[Young Ed]

Ya and wire does keep going up. The same battery cables I bought for my coupe last fall doubled in price this spring when I bought a set for my truck. BTW what is the factory spec on battery cables? I bought 1 gauge.

[Norm's Coupe]

Ed, I'd have to look that up in the book and don't have it handy right now. 1 gauge may be ok. I'm running O gauge on my coupe though. I did not look up the right gauge when I bought my cables. I just went by what a mechanic told me to buy. Some people even use OO gauge. I'll look later this afternoon to see if I can find it in the book.

One other point about wire gauge. I realize DC and AC are different. However, most wiring in a house is only 12 & 14 gauge for the whole house. There is very little 10 gauge, if any. With that in mind, it doesn't take much to light up a little tail light or parking light bulb, or to blow the horn.

[PatS....]

I'm going with 16 g. for everything. I did that on my old '50 Dodge and it worked fine.

I use a 4X8 sheet of plywood and a magic marker. I draw the parts onto the board, some get mounted to to the board, like the instrument cluster. If I make a mistake (ya right) then I can fix it there. I wrap what can be wrapped and then do the install and wrap the rest then

[Normspeed]

Pat what do you use for the wrap? Electrical tape looks like the original stuff but wouldn't that get kind of sticky and gooey after long term exposure to heat and fumes in the engine compartment?

[Plymouthy Adams]

Only tape that I am aware of getting gooey sticky is the old cloth electricians tape..it is a pain...if using regular vinyl electrical tape you will find it is a snap to use, clean and stays in place very well and protects your hearness...you can if you like just put a wrap at random with the tape..then ber the split hardshell covers to go over the harness. rather bulky and lacking in taste but doable.

[PatS....]

Pat what do you use for the wrap? Electrical tape looks like the original stuff but wouldn't that get kind of sticky and gooey after long term exposure to heat and fumes in the engine compartment?

I'm in Canada...I use hockey tape!!!!

Used for wrapping the blade and handle of a hockey stick. No good as electrical but I found it's great for wrap.

A decent sporting goods store down your way may have it. Plentiful up here:D

http://www.americanhockeycenter.com/hockey_tape.htm

[Don Coatney]

I'm in Canada...I use hockey tape!!!!

Used for wrapping the blade and handle of a hockey stick. No good as electrical but I found it's great for wrap.

A decent sporting goods store down your way may have it. Plentiful up here:D

http://www.americanhockeycenter.com/hockey_tape.htm

Thought we covered this subject a few days ago.

[55 Fargo]

Pat, are you running a 6 volt system, I have some, well actually all of my lights with the exception of the wires running to the front lights from the terminal block which are 12 and 14 gauge. the rest of the lighting wires to the rear of the car and swirtches are 16, will replace with correct color code and 14 gauge wire. The heater motor does call for 12, and the horn is 10 or 12, these could probably be 14. In fact could you not put fusable links, or a fuse panel running all of the electrical, Princess Auto in Canada sells all of the wiring items I need, but Napa has better terminal clips and hardware. Oh just go to Wallyworld for the hockey tape....Fred

[55 Fargo]

Pat, are you running a 6 volt system, I have some, well actually all of my lights with the exception of the wires running to the front lights from the terminal block which are 12 and 14 gauge. the rest of the lighting wires to the rear of the car and swirtches are 16, will replace with correct color code and 14 gauge wire. The heater motor does call for 12, and the horn is 10 or 12, these could probably be 14. In fact could you not put fusable links, or a fuse panel running all of the electrical, Princess Auto in Canada sells all of the wiring items I need, but Napa has better terminal clips and hardware. Oh just go to Wallyworld for the hockey tape....Fred

Another thing, when rewiring, this could be a good time to pull the dash, clean up under there and clean and paint the dash. I have the Model 54 dual heaters, but will probably fun just the right side with the fresh air intake for now. they are pretty dirty, filthy at the moment, but the motors run and the cores don't leak.........Fred ps does everyone use the one under the dash light for the hand brake indicator, I was thinking of running a small seperate light for that and to use both under dash lights for the door switches, I have them both on the under dash toggles switch right now, the dome light works from the pillar switch only, and I am still using the oem style brake light switch, it works fine.

[Norm's Coupe]

I with Tim on the wire wrap. I just use the plastic electrical tape for that. As Tim mentioned that other cloth type electrical tape gets sticky and gets all over your hands (worse that paint and grease) after it gets old. I have worked with the cloth type years ago as a kid when I would work for my grandfather on a wiring job in homes. Never did like that stuff, doesn't stick as well as the plastic stuff either IMHO.

If you really want to be original though there is an automotive cloth electrical wrap tape you can buy. Not sure where. My son being as picky as he is keeps telling be I should use it when wrapping the wires in the car. As mentioned though, I just say ok;) , and go back to my plastic electrical tape.

[Young Ed]

Not sure how true this is but I heard that just before or after WWII Chrysler started using the plastic electrical tape. I believe it also said they had helped create it or gotten 3m to create it for their use or something.

[Plymouthy Adams]

Pat..16 is too light..especially with 6 and on some 12 volt circuits..even with all my new stuff in my 41, I still have plenty of 10 guage wires, even have a couple of 8 gauge in there as main feeders...16 guage and 12 volts upgrade with standard circuits that were normal with your car...may bet by..byt still recommend a bit havier on the headlights, generator/alternator field wires etc.