Cummins ISL CM850 (2003-06) Fault Code: 147 PID: 91 SPN: FMI: 1 Accelerator Pedal or Lever Position 1 Sensor Circuit Frequency – Data Valid but Below Normal Operational Range – Most Severe Level. A frequency of less than 100 HZ has been detected at the frequency throttle input to the ECM.

The frequency throttle can be used in conjunction with a voltage throttle or by itself.

Possible causes:

1)Open circuit in the frequency throttle signal wire.
2)Shorted to ground frequency throttle signal wire.
3)Failed frequency throttle.
4)Incorrect frequency throttle reference (input) voltage.

Possible repairs:

1)Repair or replace the frequency throttle.
2)Repair or replace the frequency throttle reference (input) circuit.
3)Repair or replace the OEM harness.
4)Replace the ECM.