Posted on by

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

Idle Validation Switch Circuit


Overview

CODE REASON EFFECT
Fault Code: 431
PID: P091
SPN: 91
FMI: 2/2
LAMP: Yellow
SRT: 

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

None on performance.
Idle Validation Switch Circuit
SMALL | MEDIUM | LARGE

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
Avatar photo

Published by Jack

Hello, I'm Jack, a diesel engine fan and a blogger. I write about how to fix and improve diesel engines, from cars to trucks to generators. I also review the newest models and innovations in the diesel market. If you are interested in learning more about diesel engines, check out my blog and leave your feedback.