Wiring Harness Question Guru's come here please!

[demon340v]

OK guys i got a question, is there a std guage wire for the wiring harness?

I'm goign to attempt to make my own wiring harness and well  is there any specfic size wire i'm supposed to use? the connectors i think i got pretty much covered. i just woudl liek to knwo the guage wire for teh light harness, tail lamps engine harness so on and so forth.


Any help is appreciated

[moparrr07]

from what i see in diagrams it says that early cars have 18 gauge and later cars have 20 gauge, im not sure what the cut-off year is but i think 69-70 is the change, i put in 18 gauge in my 72 because thats what auto meter recommended

[Jim_Lusk]

Each circuit is different. You really need to look at a factory wiring diagram. The aftermarket ones don't have guage sizes.

[demon340v]

Each circuit is different. You really need to look at a factory wiring diagram. The aftermarket ones don't have guage sizes.

My Dad lucked out and hsi wiring diagram shows the guage for his 70 Runner   Seeing my Demon is a 71 i picked up a new wiring diragm since i lost my other one and i can't really recall the guage wire being on there.

Jim do you knwo of any place i can look for this?

[flyboy01]

It really depends entirely on how much power you run through (current/amperage) your wire.

Here is a rule of thumb I use:

20ga -   5A fuse - temp sensors, fuel injectors (rarely used in old cars)
18ga - 7.5A fuse - small stuff, like guage lights, relay triggers, sensors, etc
16ga - 10A fuse - Car radio, turn signals, dome lights
14ga - 15A fuse - Ignition, coil, cig lighter or accy tap, brake lights, speaker wire
12ga - 20A fuse - High power ignition systems, small speaker amps, headlights,
10ga - 30A fuse - single speed electric fans, better for headlights, relay power feeds.
8ga  -  60A fuse - High power amps, dual speed Viper fan
2ga -   Battery Cables.

[68_Val_Sedan]

 


Flyboy has it covered ....

[demon340v]

Thanks guys for the help

[Jim_Lusk]

You can use the wiring diagram for the Road Runner. The wire sizes would have been the same.

[moparrr07]

Each circuit is different. You really need to look at a factory wiring diagram. The aftermarket ones don't have guage sizes.

what i stated was from Chrysler service manuals - autometer recommends 18 gauge

[74swinger]

Each circuit is different. You really need to look at a factory wiring diagram. The aftermarket ones don't have guage sizes.

what i stated was from Chrysler service manuals - autometer recommends 18 gauge

I have the factory manual for a '74 Swinger and there is very little 20 gauge wiring (some for the instrument cluster lights, seat belt interlock crap, other misc lamps in the passenger compartment).  Each circuit should be considered separately - that's why almost every possible gauge of wire is used in every car.  By the way, nothing stopping you from upgrading from termination to termination if you want.

[flyboy01]

On modern cars, some wire have very little current running through them, most ase just sensors and signals. On a new 300C, there is over 400lbs of wire in the car, so they teld to use the smallest wire practical to save weight, and the cost of copper. Unless you are building a lightweight race car where weight is an issue, there is no reason to go with wire smaller than 18ga.