flight systems has manuals for all GE controllers
you can use them for general troubleshooting
but if you want specific settings for 'yale' you will need the yale manual , more to the point the 'setup' section to insure you are putting in correct values per the model , voltage, size motor and panel type etc.

check your battery maximum volts, after charging it should not exceed 57.6v(for a 48v truck), if it does then your charger is overcharging the battery causing the truck to trigger this code.

Plus this truck has 2 controllers, one for each motor and each controller will have to have function 15 set to a specific value

Left Controller Factory default value should be 186
Right controller Factory default value should be 255
(this is assuming the controllers are GE SX controllers)

This truck was also manufactured as an AC drive truck with a zapi system in it.
You might want to insure what system is in it before using my advise.