From what I understand, the later models have mileage etc on them the earlier ones don't.
Got my '91 put into my '90. From what I can tell, consoles from a '91 and '92 are the same as the ones for the '90 and earlier, with the difference I've seen as being the light 'cages' and their switches are different. but the computer is the same, and outwardly they look the same.
Not having keyless entry, I pulled that from the harness as it was just useless and more wiring I just didn't need. I can give you the wire colours on the '91 overhead if you need.
Now, looking at the pics I"ve taken in doing this project, here's what I have, using the large six wire plug that is for hooking up the overhead console.
my 1990 Pioneer: [mine had temp sensor wriing, and plug tucked way up under the dash]
white/black ; black/orange ; orange/green
pink/purple ; blue ; orange/black
the courtesy lighting is simple three wire pink ; black/white ; black.
1991; dash wiring
white/black ; black/green ; black/blue
purple/green ; blue/red ; orange/black
[note. The blue/red actually has two wires on the overhead side, only one on the dash side]
the courtesy lighting is again, pink ; black/white ; black
1989 Laredo:
white/black ; black/orange ; orange/green
pink/purple ; blue ; orange/black
Not having keyless entry, I've not bothered with that at all, but on the '91 I suspect the red connector is for that.
[For a '91 up to ? into a '90 or earlier:
find the courtesy lights, and unplug them [I just cut it, leaving the connector and tail in case I want for future use.] I used the console side connector from the donor vehicle. Look carefully up in behind the dash to see if you have the actual connector needed. Mine had this, and the temp sensor harness. I know not all pioneer's have the temp wired in, as well as not sure about lower models harnesses, so I'll be dealing from my '90 pioneers' point of view, but should be similar for other years from what I can tell.
Here's how I've wired it up so far, not including keyless wiring lookin at it from console >> dash: [type in red I"ve thus far not hooked up, and haven't noticed anything not working, but don't know what they're for, other than it's not for keyless entry]
white/black <<>> white/black
<<>> black/orange
purple/green <<>> orange/green [temp sensor interchangeable]
black/blue <<>> pink/purple [temp sensor interchangeable]
<<>> blue
<<>> orange/black
pink <<>> pink
yellow <<>> black/white
black ; black/green <<>> black
orange/green <<>>
blue/red <<>>
What I suspect from carefully looking at the connectors and how they fit from the two years. [damn, should have done this earlier I guess! DOH! Anyhow,
black/green <<>> black/orange [black/green is the grd for the compass]
blue/red <<>> blue [what do these actually do?]
orange/green <<>>
<<>> orange/black
which would lead me to think that the orange/green connects to the orange/black, but no idea, and again, no idea what they do.
Anyone have any info on those lsat wire groupings? Would be greatly appreciated!.
[Thanks very much to CollinM and Backdraft who both helped with my questions about this isntall]