1970 Wiring Guage to Use

[caffeine27]

Can someone advise me on what wiring guage I should use for my 1970 GTX.
Thanks

 

[eric383]

It depends on what circuit. The higher the load the bigger the gauge. When in doubt go to a larger gauge wire.

 

[caffeine27]

I plan on replacing the wiring on my car, slowly but completely. I have problems with lights, dash, etc.

 

[mopar 3 B]

Got a manual with wiring diagrams it will tell you what size should be there just do not go under the stated sizes.

 

[Shorthorse]

You didn't mention exactly what electrical issues you were having so I've got to ask. Are your current wiring harnesses in bad shape? Have you determined the issues you currently have are due to the wires themselves? The reason I ask is when you just replace the wires and have to splice to all the original connectors, you can create more issues than you started with. That would include the integrity of all the splices you will need to make and the addition of more "points of failure". The connectors themselves could be questionable so using the existing ones may solve nothing.
If you don't want to splice, finding the exact connectors, lugs etc, can be difficult. Sometimes the cost of a good used or new aftermarket harness is actually less in the long run. It's certainly less labor intensive than doing a few wires at a time, over a long period of time. Also, a good used or new aftermarket harness will also have the same color wires as the originals, which will save a lot of headaches down the road.
However, if you are going to do your own wiring, as eric383 said, the gauge depends on the components you are feeding. Be prepared to buy lots of wire and pick your wire brand carefully. The internet is full of information on wire configuration, load capacity, resistance and insulation properties. This site also has some good posts on crimping vs. soldering or using both.
http://www.mymopar.com/downloads/1970/70BelvedereGTXSatelliteRoad RunnerA.JPG
http://www.mymopar.com/downloads/1970/70BelvedereGTXSatelliteRoad RunnerB.JPG

 

[eric383]

X2 on what Shorthorse said. If you have a bunch of re-wiring to do it may be better to get a new wiring harness.

 

[caffeine27]

Ok Shorthorse and eric383 I will start with harnesses. How many are there and where are they located? Again sorry I'm a below novice car guy.

 

[Shorthorse]

There are 3 basic harnesses.
1. The engine compartment harness which consists of everything forward (lights, Ignition, sending units etc). They plug into the bulkhead terminal on the firewall. As long as we are speaking of the bulkhead terminal, make sure it is clean and visually inspect all terminals within. For some reason, Mopar bulkhead terminals seem to be the cause of a lot of issues over time.
2. The "dash" harness. That speaks for itself (dash gauges, lights, ignition, heater, wipers, AC or not and so on).
3. The rear harness. That harness feeds the rear lights, and sometimes the fuel sending unit.
There are other small harnesses depending on options such as consoles etc.
Again, you didn't mention specific issues or the condition of your existing harnesses. Maybe you could list some of the
problems. There's lots of talent on this site. Might save you some money.
But new harness or not, check ALL your grounds now. I don't have any statistics but I'd bet more than half of all electrical issue can be attributed to bad grounds. I've learned over many years that the goofier the problem is, the better the chances are it's bad grounds.

 

[caffeine27]

Thanks a bunch. I will do as you suggested. Do you have any pictures of the harnesses by any chance, and position of them in relation to the car.
My car is a a 1970 Plymouth GTX. Automatic with 440 and a Six Pack added. I have the Rally Dash, Radio and no other options.
My current Electrical issues are the following.
1. Lights work most of the time, but side signals don't work. Sometimes when I swtich from regular to High Beam the lights go out and only the high beams work, but side signals will then work. It is very intermittant. High beam indicator on dash works sometimes.
2. I have no dash lights. The interior lights work (dome and centre console), but no dash lights
3. Reverse lights are always on when in drive. I have another post about this and I believe it is the NSS switch
4. Radio does not work.
That's it for the moment, and thanks.

 

[Shorthorse]

I know you mentioned your "below novice" status but it's time to get acquainted with your car. Tackle one issue at a time and try not to get sidetracked. Enjoy learning.
Just for a drill, lets look at those side marker lights. Keep in mind the side markers are running lights only. They only have one element and do not work as turn signals. Take a look at the A.jpg I attached earlier. Don't be intimidated by wiring diagrams. If you can read a map and get where you're going, you can read a schematic. The top left corner shows the right marker light. The black wire is the ground and the black/yellow tracer wire is the power. Notice the black/yellow tracer wire also goes to the right parking light. Does the parking light work? If it does then you have 12V out there on the harness. Look further and you see the black/yellow tracer extends to the left side also. The black/yellow tracer then goes to the bulkhead terminal #3/connector "U". That's where it goes into the interior and becomes part of the dash harness as a yellow/tracer wire. If none of the markers or parking lights work then we need to go inside and follow the yellow/tracer that eventually ends up at the panel light dimmer switch and light switch.

 

[caffeine27]

Shorthorse. I will do exactly as you said this weekend and get back to you.
Your correct I'm working on too many things at once.

 

[caffeine27]

Thanks for everyone's help, epecially Shorthorse. All lights working now. It was a problem at the fuse box wiring harness. Boy my fuse box is old and looks like it's just waiting to cause problems.

Well on to the interior lights.

Thanks again.