I've got the '83 FSM printout for how the oil & volt gauges connect with things. Problem is, it doesn't make much sense to me. I'm not sure that my truck is already wired for them, since it didn't come with them from the factory, so I'm figuring out how to run the wires. I just can't quite get what the diagram is saying. I don't really know how to post an attachment other than a photo or I'd post the page I'm looking at. But anyways if anybody has any info I'd appreciate it.

Even if someone could help explain how you tell which is a + wire and which is a -?

 

wow this is a tough one to explain if you have no real background or classes taken in it.

You essentially have to follow each and every wire at a device in the diagram to see how it connects or interfaces with other wires or other devices.

You have to assume each device has a positive and a negative wire-red is a typical power color-but not always. Green is a typical ground wire-but again not always. Some devices-like a horn-ground themselves with their body mounted to the "ground" the frame of the vehicle.

What you are looking for for the oil and voltage gauges would be extra "plugs" that are not at this time plugged into anything.

I hope this is somewhat helpful but I think a more productive question would be for you to post in first gen section-like for the Runners for example 84-89

Some thread title like "Could I be pre-wired for oil and voltage gauge?"