Neil, you will need to have the local Hyster dealer to reset and give you the password for this truck, and there are a few levels of passwords. no one else other than Hyster dealers will have the software to be able to access the passwords, and very few people other than Hyster dealers will have the experience to help you with this truck
676-4= Glow Plug Relay Driver Output Out Of Range Low
I take it this is a deisel truck.