I'm going to disagree with Pete slightly, but I don't think it will help you.
Over the years Lionel issued 47 supplements to its original service documentation. Extending into the late TMCC years these cover many, many models and have a large number of wiring diagrams, but alas, not for yours. It cannot be found in any of them for some reason.
Pete's suggestion might be your only option. Using the part numbers for your motherboard (691-PCB1-10F) and DCDS (691-DCDS-YU1) in your search might help. From lionelsupport.com:
Mike