It is usually a bad Q-1 transistor. It is available in a kit part # 828-900-101. Just going by memory on the part#. There are a few tests that can be run in the on board diagnostics and then the Q-1 can be tested with a Fluke meter. Also look at the drive motor brushes and the comm. on the motor, if they are very worn or burnt it could cause the code. It is also recommended to replace the power card if the Q-1 is shorted. Good luck.