New here; need tips Delco mid-1990's slave CD player in GMC pickup

Guess that says part of it............
New here; 1st real post after intro. I drive a few older vehicles and often like the original audio equipment. Recently purchased a high mileage 1996 GMC 4WD K1500 pickup with what was then apparently an upper end audio package. AM/FM, Cassett and slave, separately mounted single CD player. All worked except CD player; just displays, "Err," when CD inserted. Common problem it seems. I see some folks have good luck cleaning the laser with alcohol swab and very light lube on gears, etc., but I can't see how to access all that. I got a second unit from wrecking yard. Works perfectly, except........will not eject CD. I opened it up and found the micro-button to eject on the first PCB was intermittent or, most often, just always open. I got all that fixed. I would like to test this on the bench as I have a 3rd unit now in the truck that works. (I don't want to pull the truck apart again right now.) So I'm looking for a schematic that will tell me what punchings I can use to apply voltage to test ejection. Have had no luck on line, yet. Unit is a Delco Model 1623 1055. They were used a lot during the mid-1990's in GM pickups and cars. Mounts separately from main radio/head. Anyone have any idea where I might find a wiring diagram????? Or general suggestions? Thank you, Dennis

 

Guess it's time to give up on this thread. Oh, for the days of Sam's Photofact sheets.
Therefore, having no other non-destructive information, I've decided the only way to, "bench test," ejection function of this slave CD player is to in stall it back into one of the pickups it came from so I'd have all the proper cable/power connections.
Thanks anyway.

 

I guess the only alternative would be to get another head unit and the matching wiring harness. If the wiring harness is part of the trucks wiring even that might not be practical.

Sorry nobody could be of help but there is probably less information for factory supplied audio units than after market ones, which would at least come with fitting instructions.

 

Thank you. Actually, that techno magazine link was helpful. Might be as close as I'll ever get. Last resort will be to swap units with working vehicle's system.
Merry Christmas, Dennis