Accelerator Pedal or Lever Idle Validation Circuit – Voltage Below Normal or Shorted to Low Source
|Fault Code: 551
Accelerator Pedal or Lever Idle Validation Circuit – Voltage Below Normal or Shorted to Low Source. No voltage detected simultaneously on both the idle validation and off-idle and on-idle switches.
Automotive: Engine will only idle.
Marine: Severe derate in engine speed. Limp home capability only.
Accelerator Pedal or Lever Idle Validation Circuit
The idle validation switch is used by the electronic control module (ECM) to indicate when the accelerator pedal or lever is released (on-idle) or depressed (off-idle). The switch is adjusted by the accelerator pedal or lever manufacturers to switch from on-idle to off-idle at the correct accelerator pedal or lever position. The switch return is a shared return with other OEM cab switches.
The integrated sensor switch (ISS) is located on the accelerator pedal or lever assembly.
- This fault code is usually caused by a short circuit to ground in the harness, an uncalibrated accelerator pedal or lever assembly, or a miswired idle validation switch.
- When installing a new accelerator pedal or lever 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 or lever three times.