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Here's other problem related to that 634 error code.
(R) = Engine Running test (M) = Memory code (O)=Key On Engine Off test
634 (O,M) = Park/Neutral Position (PNP) or Clutch Pedal Position (CPP) circuit fault Electronic shift transmission - Manual Lever Position (MLP) sensor out of range in Park-Transmissions
Now sure where to go from here but I would try to remove the connectors and clean them and see if that makes a difference.