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

Description

ISS Goes to 70-fc 431iss

Possible causes:

1)A open circuit on either the idle validation on-idle or off-idle signal circuit, a loose connection, uncalibrated accelerator pedal assembly, or miswired idle validation switch.
2)The integrated sensor switch (ISS) has a different internal resistance specification (125 ohms) than the nonintegrated sensor switch (NISS).
3)When installing a new accelerator pedal assembly, it must be calibrated before operating the engine. To calibrate, turn the keyswitch to the ON position and fully depress and release the pedal three times.

Possible repairs:

1)Connect the ISS to the OEM harness.
2)Replace the ISS.
3)Repair or replace the OEM harness.
4)Replace the ECM.