Automotive Wiring

Someone on reddit asked for general advice on wiring. This excellent checklist was posted by @tropical_cowboy:

Understand:

What a ballast resistor does and where it goes.

How to wire an alternator with or without a regulator (one wire) decide before you start. Upgrade now, or learn how to wire the generator and be disappointed.

Know that you are supposed to have a ground from engine to frame, frame to body, engine to body, battery to frame, battery to body.

Also make a dedicated ground wire from your gauge cluster to dash.

Find the main switches and components, make a map, then find the circuits so you can loom before you install.

All holes must have grommet.

Have a small battery and test every light bulb you replace in its socket, using the leads, before you plug them in.

Replace every bulb

Turn signal wiring is confusing, get a diagram before you start.

Adding a under hood light, or even a few lights in the bed, may be worth it.

Map your dome light circuit and find the dome light lead before you run the main harness.

Get new dome light switches.

Understand that some parts of the harness are long wires running with groups of wire that may be intended to have multiple destinations. Meaning if you are not paying attention it’s easy to run a wire the wrong way just because it’s with some other wires.

Pulling an extra open wire or circuit to the front and rear of the vehicle, to under the dash, will allow you to add a circuit you may have forgotten.

Most “upgrade” harnesses have a keyed “electric fan” wire, this is a signal wire nothing more. You need a relay at the end and a direct fused battery source for the fan itself. You also might need the ground signal from a thermostatic sender if you don’t want it on all the time.

Run all the wires there to the right spot even if you do not have the accessories.

Test your fuel sender and fuel gauge in your hand with test leads before installing, if it works now take it out, inspect and maybe replace, then test.

Find your neutral safety switch before you run the harness

Find your backup light switch before you run the harness.

Verify any transmission connections you may have, I don’t think you have any on a 1959 ranchero but just in case.

Get new senders and install with new wires.

Test ground continuity between parts often while reassembling.

Get a new battery.

Install new battery cables.

There’s more, but honestly it’s a simple job, but it has LOTS of steps so like everyone said here, one bite at a time.