Cummins ISX CM870 (2003-06) Fault Code: 431 (NISS) PID: S230 SPN: 558 FMI: 2/2 Accelerator Pedal Idle Validation Circuit – data incorrect. Voltage detected simultaneously on both idle validation and idle validation off-idle validation switches.

NISS Goes to 70-fc 431niss

Possible causes:

1)Open circuit on either the idle validation on-idle or off-idle signal circuits, a loose connection, uncalibrated accelerator pedal assembly, or miswired idle validation switch.
2)The nonintegrated sensor switch has a different internal resistance specification (10 ohms) than the integrated sensor switch (ISS).
3)When installing a new accelerator pedal assembly, it must be calibrated before operating the engine. To calibrate, turn the keyswitch to ON position and fully depress and release the pedal three times.

Possible repairs:

1)Connect the NISS to the OEM harness.
2)Replace the NISS.
3)Repair or replace the OEM harness.