My Ranger has rear speakers, and I have recently been trying to apply some instructions i'd seen in an old april 1992 issue of Stereo Review that detailed surround sound, in a do it yourself fashion. the following link is not from the article, but details in the same way what appears in the magazine.
Poor Man's Surround Sound: 4 Steps and, without needing or having to install a special decoder.

so, my point here is, the rear speakers are connected correctly to the main factory wire harness at the back there, as they were originally at the factory. per the information in the link above, what would be the proper way to modify the wires between the speaker connectors on the harness, and the ends of the connectors that plug onto the actual speakers? as it seems that this factory harness has two wires in it for each speaker, but per the web site there, it seems that only the positive wires are needed, with the negative points of both speakers being connected together with one wire separate from using the two negative wires from the harness and connectors.

i had this all connected per the web site and magazine article, but have had to replace some things and just wanna make sure i get things connected proper again, per how the web site suggests. thank you.

 

There were two different audio systems offer in 1990-1992 Ranger

Wiring diagrams here: Ford Ranger Radio Wiring Diagrams : The Ranger Station

Yes the "-" wires are Radio grounds(not truck grounds), it is the reference signals, so all 4 speakers can share one "-" signal or 3 or 2 speakers, same "reference" signal for all

"+" wire needs to go to "+" terminal on the speaker, this keeps the 4 speakers in the same "phase"
Speakers do not have an electrical + or -, it is just a coil of wire inside, this is an audio phase + and -

You could hook "+" wires on all 4 speakers to "-" terminals on all 4 speakers and it won't effect sound quality, but if just 1 or 2 of the 4 are reversed then they will be "out of phase" with the other speakers and the audio will sound "muddy".

Most 4 speaker systems have Balance control, Left and Right, and also Fader control, front and back, so you need to keep track of what "+" wire goes where to keep those controls correct

Not sure what you mean by "surround sound"
In TV rooms it means rear channels are delayed or ahead of front speakers, to give the audio illusion of motion going behind you or coming up from behind you.

For music in cars/trucks the rear speakers are usually just larger than the front to give you more "bottom end" lower frequency.
Higher frequencies are easily blocked and don't travel far, so they are closer to front, usually in the doors, and only need smaller speaker cones
Lower frequencies need larger speaker cone and carry quite well.
i.e. you can hear the thumping bass from a subwoofer 5 cars behind you at a stop light, lol, can't tell what song it is but low frequencies carries a long ways

 

thank you ron. i actually already have a ford workshop wire diagram, so i already know, per factory, which wires go where, for speakers and head units, and their respective connectors.

the main question in my post, is in reference to the link i included for 'poor mans surround sound'. regardless of if its for a home set up or not, the instructions there would apply to any speaker set up of at least 4 speakers.

i previously had my rear speakers connected per the web site's instruction, but based off a 4 channel amplifier. that one has since been replaced with a 5 channel. the speaker wires are still connected appropriately for the rear's, as the were before, but this time im not hearing anything from those rear speakers, when i used to with the same 'surround' set up that i had with the 4 channel. i tested the speakers separate from the vehicle and they do work, so its not the speakers. the wire harness that ties into the head unit and goes to the amplifier has the rear speaker wires connected properly. --none of that has had to change between the two different amplifiers.

i guess what im wondering, per the web site and how the wire connectors are set up from the main wire harness to the speakers is; do i just remove the negative wire from the connector to the speaker for both speakers? and then, just connect another wire from each speaker's negative/- tab and be done with it?? that seems what is shown at the web site.

 

Well then, I guess we can nevermind all this, as I found the problem...

It seems while I installed the new amplifier, one of its attachment screws was too close to the rear right speaker wires from where it meets the main harness extension thats on the floor. The one which eventually goes up to the head unit wire harness.

The rear right wires are brown white and brown blue. One of these two was cut all the way in half when putting in one of the amplifier installation screws.

I knew there were wires three, and was 100% careful to align those away from where the screw was going into the cabin metal. It seems I wasn't careful enough.

Alls this will need is a butt splice for reconnection. I think now my issue is solved.

 

Good work solving the problem

 

That you for the detailed description; Im adding speakers to the back and replacing the stock one's in the door. Thanks again