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.