Wiring diagram circuits decoder?

[ncrobb]

Looking at the factory 1973 Service Manual wiring diagrams and I have some questions that I can’t figure out or want to be sure on. Say for instance I’m looking at the engine compartment diagram and I see the G2-20V wire from the bulkhead cavity 21 to the temperature sending unit. In the “G2-20V” I am pretty sure the V is for violet as in the wire color. Is the 20 the wire gauge? What does the G2 represent? So similarly the R6-12BK runs from the bulkhead cavity 18 to the alternator output. It’s a black, 12 gauge wire?

While I’m asking I’m guessing it’s ok to use a larger gauge wire than called out like using an 18ga or 16ga in place of 20ga but certainly not a smaller one? Other than economics is there a time where larger diameter wire is detrimental?

 

[ncrobb]

Nevermind, Google is your friend.

 

[Bobby Goolsby]

Nevermind, Google is your friend.

What did you find?

 

[Nxcoupe]

Yes, you are correct. Mopar still does it that way.
Ie. G405 will be a ground where a screw actually grounds the wire to the body.
Later they went to letters with the circuit numbers, like above. Each letter tells you what the circuit is. I'm not positive the older stuff is like that.

 

[ncrobb]

MyMopar.com has some info on what the circuit numbers mean. The big thing for me was confirming the color and wire size.

 

[Nxcoupe]

MyMopar.com has some info on what the circuit numbers mean. The big thing for me was confirming the color and wire size.

So what you are saying is that the early cars did it that way also?

 

[ncrobb]

Yes. For the G2-20V the “G” is gauges, still not sure what the 2 is, 20 is the wire gauge and V is violet. The R6-12BK: “
R” is the charging system, still don’t know about the second position, 12 is wire gauge and BK is black. So there is a cadence. “A” is battery, “J” is ignition, “V” is wipers, etc.

 

[Nxcoupe]

Yes. For the G2-20V the “G” is gauges, still not sure what the 2 is, 20 is the wire gauge and V is violet. The R6-12BK: “
R” is the charging system, still don’t know about the second position, 12 is wire gauge and BK is black. So there is a cadence. “A” is battery, “J” is ignition, “V” is wipers, etc.

Letter is circuit type, number is circuit number so you can track that circuit on different pages/diagrams. The next number is the gauge of the wire and then color as you stated.