Hi rafael,
First you need to test the commutator on the drive motor, disconnect the battery and connect a test meter across the A and AA (armature) set it to continuity and manually turn one of the drive wheels to rotate the drive motor watch the meter and make sure that you have continuous continuity on the drive motor com if not you have a drive motor armature fault.
What type of GE controller is fitted on the truck thyristor, MOSFET / IGBT or sepex (I think it is a MOSFET / IGBT with 3 big blue capacitors with an NY logic) if you are not sue can you describe it.
Regards Shane
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