CM870 and ISX Engines – FAULT CODE 551

Accelerator Pedal Idle Validation Circuit


Fault Code: 551
PID: S230
SPN: 558
FMI: 4/4
LAMP: Amber

Accelerator Pedal Idle Validation Circuit – data incorrect. No voltage detected simultaneously on both idle validation and off-idle validation switches.

Engine will only idle.

Accelerator Pedal Idle Validation 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 solid state sensor switch (SSS) is located on the accelerator pedal assembly.

Shop Talk

  • This fault code can be caused by a short circuit to ground in the harness, uncalibrated accelerator pedal assembly, or miswired idle validation switch.
  • 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.

Refer to Troubleshooting Fault Code t05-551sss

Last Modified:  01-Sep-2010