you can attempt to purchase a service book from your yale dealer, there is no guarantee they will sell it to you though. They might , then again they might not.
Based on your description and comments and the fact you are new to lift truck repair i'll say this:
- based on the model of this truck even with a service book you will be challenged to attempt to repair this truck
-other than checking fuses and battery you would most likely need the pc program to aid in further diagnostics

so based on the codes being displayed i would do this
a) check the battery charge, if it is a flooded cell battery make sure the water level is above the cell plates and make sure it is charged up.
a low battery can cause these codes. If the battery is charged and no other issues are found then there may be some other problem with the bdi circuit and/or configuration in the vcm.
b) remove the control panel cover which should be located underneath the seat/hood and gain access to the components on the panel and locate any fuses you can find and check them with a vom, The may be fuses located underneath the floor plates or on/in the steering column as well, i would suggest removing them from their sockets first and check them with the vom in ohm or resistance scale, they should read infinity on the meter, any open or excessive resistance indicates a potential issue and the fuse should be replaced.

Beyond this i would call a dealer to send out a tech