Code E151 - Drive Communication Tx Error
Short or open circuit in CAN wiring.
Electrical noise in CAN wiring caused by bad connection, outside
interference, or low voltage (especially while lifting or driving) possibly
caused by over-current or short-circuit. Check CAN wiring. Try driving with
a known-good battery or in a different environment.
Bad power amplifier; ETAC internal error.

Make sure the battery voltage isn't dropping off when powering up (most common cause of code, especially with maint free batteries)
Remove the tiller arm at the drive unit, inspect the main wiring harness for chaff's where it flexes when turning.
Check the brake for a short/open
Check the main contactor for short/open.