I want to repair/replace some frayed underdash wires for a 1941 Chev Master Deluxe Business Coupe.

In previous threads on this forum I get the impression that Chev used color-coded wires either to identify use or gauge or both. Does anyone have a chart that matches the colors with the use of wire, (horn; radio; heater; etc.) or color with gauge or both?

As I look at the various colors currently used on my unit (green with yellow stripes; white with blue/black flecks; and lite brown) they all seem to match either 10 gauge or 12 gauge wire in thickness. Is this correct?

Does a gauge number change with 6v or 12v or is the gauge number generic?

How important is the gauge number? For instance, what damage can I do if I use 10 gauge and it should have been 14 or the other way around?

Hi Dr David,

Let's see what I can do for you.

Wiring in a 1941 would have some means of identifing each wire, however I have never run into such information.

Your best bet is to purchase a new wiring harness. The new harness will come with coded wire and a map to decode each color (actually the wire will have a band at each end which will identify each wire).

The reason for recommending a complete harness is that there are several junctions of the wires that go in more than one direction. If you were trying to replace it wire-by-wire you refrigerator would not hold enough liquid to complete the project.

The gage of a wire will vary based on the use and voltage.

You may be thinking backward on the gage of wire. For example an 8-gage wire is much bigger than for example a 18-gage wire.

Shooting from the hip, your car will have one wire that is 10-gage (starter to ampmeter) and most of the others are 16-gage. If you apply too much current to a small wire (18-gage) it will do bad things and tend to smell.

The radio and heater wires will not come with a new harness as they were items added to the car later.Would depend also as to what heater and radio you have.
The 12 volt cars use a lighter gauge (thinner) wire -they carry more volts but fewer amps.

Thanks for the info. The new wiring harness is the best of ideas, but I think I'll pass at this time. All of my systems (except radio and heater) work; and even there I think the problem is with the units themselves, not the wiring to the units.

What I have are some wires that over time have frayed and are exposed. In some cases the previous owner spliced into a wire and the tape has come loose. I'll planning on replacing frayed wires with new tape and updating splices with plastic and metal oens and connecting them directly to a power line rather than splice into another one. I have installed a fuse box under the dash to connect spliced wires directlyinto.

Thanks for info on gauge determination. I think I have that down now. If I understand correctly the more (lower gauge) is best as it is better to have too thick of wire than too thin to aviod bad smells, shorts, and possible fires.


I would still be interested in what each of the different colors and stripes stands for -- perhaps that was the old way of showing gauge and/or where it was connected.

DML

On a different note: we spend the summers near Olympia, Wa. From what we are hearing this has been a good winter to be in AZ. Hopefully the weather is a little better in Vancover than in Olympia.

A new wiring harness makes a great Chritmas gift and also provides much peace of mind! Many of us have seen the conditions you describe and we cringe at the thought of shorts and fires...it can make a pleasant drive a real nightmare!
In the absence of a new wiring harness, please be sure to carry a good sized A-B-C fire extinguisher with you.

The idea of installing a new harness can be callenging, but it's a lot easier than you are probably thinking. They come with instructions and each line is coded to make installation fairly easy....and well worthwhile!

Coach

Coach is right. If you are going to drive your car the only safe way to go is with a new wiring harness. Sure beats the heck out of "Mickey Mousing" the wires with new electrical tape and plastic fittings.

To answer your question without telling you to buy a new harness.
I haven't been able to find the gauge value for a 41 either in the repair manual nor the parts manual, However, What I would do is to look up the 1953 circuit diagram (in the 49-53 shop manual)
The 53 used two different wiring harnesses. The early 53 used the fabric wrapped with tracer colors basically the same as a 41. The later 53 used the new plastic covered wire and it was color coded by color of the plastic insulation. Why am I telling you this?
Because the 1953 wireing circuit diagram shows the wires in the correct gauge, color code for the later models and also the FABRIC WITH TRACER THAT YOU ARE LOOKING FOR! If you need wire, check with Rhode Island wireing, they sell the wire, connectors and about anything you will need to rewire your car.
To find a 53 Shop manual wiring diagram go to: 1953 wiring diagram

All wiring on Your 1941 was originally natural (tan/yellowish) with various tracers (black, green, etc) depending on wire use. Can send you this if you like. Sounds like your car has been rewired using modern wires. If your just want to repair it I would try to find similar colors. As for gage I would use 12 to 14 with 6 volts.

And make sure you buy a ABC fire extinguisher...Oscar

16 Ga. was used for lights and things and 12 Ga. for the starter to ammeter.

First, let me thank all of your who have taken the time to respond to my question. You have been a great help in getting me on the right road.

I am fairly new to this group and have been very pleased at how much people are willing to explain what may seem to be "basic" concepts to someone who has not worked on a car since he owned a model "A" in high school in the 1950's. We bought a car with an older restoration that needs some updating, and I am doing this as one more "retirement hobby." As much as possible I'm trying to do it myself (with oversight from a mechanic and advice from others).

Second, I couldn't agree more that a new wiring harness is the best way to go, however, it is too soon for me to take on such a project. Please don't think that I don't understand the importance of how good that advice is, I just am not ready. In the meantime I will take the advice to carry fire protection.

The vast majority of the wiring looks good and everything electrical works (except radio, horn, & heater) and none of their problems seem to be due to the outside wiring but in the units themselves. I have had a mechanic look at the wiring and he told me that he sees no reason that I can't simply do some point to point replacements at this time given I am not going to be driving it much or very far in the near future.

I have a wiring diagram in my 1941 Shop Manual, but it is hard to read. Your suggestions regarding gauge and wire colors now make this diagram make more sense to me. For instance, I note they use terms such as "neutral black tracer" for a wire. Based on your input I now think that means neutral color with black flecks.

Since posting this I found a website (www.crowbar-electrical/specifications.htm) that lists the gauge for many items with the note "for 6 volt systems use next larger wire."

Again, thanks to all of you for your advice to date. Each post has been very helpful. And, please be aware I would appreciate any additional information you may have on this topic.

DML

Hi Dr David,

We have as much satisfaction in providing the information as you do in receiving it.

Good luck with you project and do not hesitate to return here for information at any time.

Seasons Greetings.

The added bonus is that not only the person asking the question learns something. I have had many questions answered before I posted them.
Tony

Wiring on an older car can be a real problem. A short or a blown fuse will have you sitting beside the road. Not much fun especially if you are going to a show or during a parade. Fire has been mentioned earlier in this thread. I rewired a '28 National Sedan several years ago using wire or cable that has about 10 to 12 wires in it. Heavy wire . Probably 10 to 12 gauge. I striped the outer rubber cover from the wires leaving about 2 feet (covered) in the center. I attached the covered cable to the cowl and ran wires to front and back. As most of you know the wiring on a '28 is minimal compared to later models. It worked perfect the first time. I was really proud of my wiring job. However when I restored my '41 Coupe I ordered a complete wiring harness. Had a mechanic friend help me and I worked out good. What is a few more dollars when you have several invested in your Chevrolet. You will enjoy your car a lot more if you restore everyting. It cost very little more to go first class. Good luck JIM