если педали Sim Pro надо педаль тормоза заземлить.
Your shipment also contains a small grounding wire. The grounding wire may be useful if you use a Direct Drive-based steering wheel (such as the AccuForce or OSW). In some circumstances these type of wheels cause interference to other electronics, which shows itself as a small jitter on the pedal output.
If this happens, you can connect the molex-connector side of the cable to one of the grounding pins of the controller. The other side can be connected to one of the bolts of the brake pedal. This should stabilize the signal.