Electronic Control System Signature, ISX and QSX15 Engines – FAULT CODE 431

Idle Validation Switch Circuit


Fault Code: 431
PID: P091
SPN: 91
FMI: 2/2
LAMP: Yellow

Voltage detected simultaneously on both the idle validation off-idle and on-idle signal pins.

None on performance.

Idle Validation Switch Circuit

Circuit Description

The idle validation switch is used by the electronic control module (ECM) to indicate when the accelerator pedal is released (on-idle) or depressed (off-idle). The switch is adjusted at the factory to switch from on-idle to off-idle at the correct accelerator pedal position.

Component Location

The nonintegrated sensor switch (NISS) is located on the accelerator pedal assembly.

Shop Talk

  • This fault code is usually caused by a loose connection, uncalibrated accelerator pedal, or miswired idle validation switch.
  • The integrated sensor switch (ISS) has a different idle validation switch (IVS) resistance specification (125 ohms) as compared to the nonintegrated sensor switch (NISS) (10 ohms).

Refer to Troubleshooting Fault Code t05-431niss.

Last Modified:  26-Oct-2010