I also have some notes that indicate that there is a possibility that some RF "noise" created (induced) by having some of the (shielded) control cables routed to close to the power cables may cause some of these codes, and have a note that adding a capacitor (like is between the connections on the coil of some contactors) mounted between the key on positive and the frame of the truck can reduce or eliminate the incidence of code 66 w.i.f.

if you don,t find a short ,pull the lid off the controller (off the truck )and look for blown out transistors.if you find some it,ll need replaced.

my book says 66 is "field current too high", disconnect power leads at traction motor and check for short circuit in traction motor, and check for short circuit between battery positive and or battery neg at F1 and F2 and battery case.
my memory says this can be caused by a crudy battery and voltage dropping out. pull the battery from the truck and check it then (battery case isolated from the truck).
151 can be related to fuse 5 being blown, and/or the battery being too low to properly charge the capacitors

get the battery checked/fixed and all that acid and corrosion out from the battery box.