You stated that it will travel, but will not turn. Can you elevate the drive wheel and attempt to turn the handle? In doing this, if there is strain on the steering bearing, it will be relieved. Also, look around the bearing that mounts the drive unit to the frame of the truck. Do you see a grease fitting, like a zirk or needle fitting? If not, then the problem will be the bearing that I have been talking about. When that bearing was put on this serial number range of trucks, the "powers that be" believed that there would be no need to grease the bearing, since it was sealed. After many trucks ran in a cold storage environment, the bearings started seizing, consequentially resulting in a service bulletin to be published recommending the bearing to be replaced with one that DOES have a grease fitting. As for the code, are the red lights flashing first? and how many flashes from the yellow lights? This code flashing on the traction amplifier has no effect on the steering problem you are encountering. Sorry for the history lesson and for being so long with this reply. I don't have a lot of time to get on this forum much, so I tend to go overboard. Hope this helps!