I looked up code in manual , 110 is slave controller VMN high
Shorted cables ,shorted motor or shorted controller
Proceed with the cables to make sure there is no frame ground and test fuse
Then if you are confident enough check the controller let me know and I can guide you through it

Always get another unit ! First check 500 amp fuse , it is main drive fuse I have seen a lot that check good under continuity but will not carry the voltage second you will have to remove battery and in battery tray there is a channel where the main cables lay over time batteries are leaking or have been over filled and acid gets on cables causing the rubber coating to expand and deteriorate and exposing the cable which can short out to frame
Also make sure they are in channel properly
If not battery will crush them
I retired from Clark dealer after 32 years
The worst case is you have a motor rebuilt or replace a controller either way much cheaper than new unit

I read your post people that can't fix something tell customers they need a new truck. With that said l will try to help you l have seen that code a few times on this Clark truck first if no one played with the drive motor cables than remove the cables and make sure you do not have a open phase in the motors. If the motors check out they usually are good than l would look for a short to frame on the drive motor cables. You will have to remove the battery and check the cables under the battery that is usually were the coating comes off and touches the frame from battery acid if you find nothing than the last thing it could be is a bad Zapi slave controller than you would have to have it looked at and rebuilt. Hope l was of help.