The title should be clear, if not: I know most auto manufacturers make a somewhat universal harness with some accessories plug ins on all cars. Is the main wiring harness from the dash to rear for the hatch release installed in cars without this option?

i have never heard of what you are talking about.
this is a learning situation for me so how about sharing what manfacturere and what king of universal harness are you talking about?
be sure to post some links the rest of us would love to know about it because in some cases we have to make our own.
and there are not many wires that go back to the hatch.
just make sure you use the hot wire than comes from the correct fuse if you have to make your own.

I am asking if GM had an accessories harness for this that was installed with the option, or if it was part of the main F body wiring harness. Not all accessories had separate harnesses.

gm has a general harness and if they had an option they did a splice and put the new harness in.
it makes since to have plug in places for wiring but that would be expensive to have every wiring harness with multiple plug in positions so all you had to do was plug in a option for the harness.
gm went the path of least resistence - want the option - they splice it in.
you already have a hot wire back to the rear - it is connected to the lights.
you have to splice in the auto hood release from the switch in the console and get your own hot wire to the auto release and pull down device.

Interesting question, one I have no answer to. However, I have occasionally read on site, for example, where a member has gone to wire up an electrical driver's seat, only to discover the plug in place. A quick look, if that's possible, might be the best answer.

JamesC

Most cars have the wiring inplace regardless of the options. Wiring and connectors are cheap, the part is the big cost

Examples:
Power seats
Foglights
Power locks
Rear defroster
Underhood light

Im not sure if the hatch release wiring is always there because Ive never messed with a non pull-down car

Even if it is missing, salvaging the entire harness will not be difficult from a JY as the bulk of it runs behind the drivers side rear panel

yes on under hood light, but i installed power seats from gm and had to search down and buy the special wiring harness for it. and when i got it there was no way to plug it into a hot wire that went into the right fuse, so i had to make one.
never had a car without auto locks so i dont know about that.
the rear window defroster takes a lot of juice and i have had 7 of these bad boys that i bought new and there was NO wire to a non existent rear window defroster.

i dont have fog lights on this one and i have had everything out from the waterpump forward and there is no harness for the lights.

sorry to bust your bubble but it just aint so.

you may find hot wires - but they have to be hot wires that go back to the correct fuse block location, not just some hotwire you cut into that is not designed for the right amps.

i have had the back of my 90 off and there is a wire for the light and a different light for the hatch and a different for the release.

so why doesn't he just pull the back - there are only 4 plactic screws - and take a look.

I put on in my car, the answer is NO. is is a special addition. if you want it, you have to pull the harness and switch for i out of a car, the 12V+ plug for it should be under your center console, plug the harness and relay into it then your switch, then run it back to your hatch release which just screws into the actual release after you cut off the little square on it

+1
i added a factory hatch release to my '84 TA just like you said. it was a pretty easy upgrade.

you have to be darn careful about what you plug into back there.
you cant just add a release from any hot wire.
there is a hot wire that is red and white that goes to the light and the hatch PULL DOWN can be added into it. see diagram.

BUT THE PROBLEM IS THE RELEASE.

YOU CANNOT USE THE RED/WHITE WIRE. it takes a special 25 amp fuse wire which is orange and takes a long route to get to the release. see 2nd diagram attached.

these diagrams are from factory wiring diagrams and there are not many changes from one 3rd get to another.

as i said, the PLUG to power the hatch release should ALREADY be in the center console. you plug the hatch release harness right in and run it back