Cummins ISM CM870 (2003-06) Fault Code: 2351 PID: S146 SPN: 2791 FMI: 4/4 EGR Valve Control Circuit – Voltage Below Normal or Shorted to Low Source. Low voltage detected at the EGR valve motor circuit.

NOTE: Prior to running the INSITE? electronic service tool EGR Valve and EGR Valve/Turbocharger Operational Test, the ECM Calibration Software Phase could possibly need to be updated to the latest Software Phase. The ECM Calibration Phase Software can be checked in INSITE? electronic service tool, under ‘Features and Parameters’. Expand the selection for ‘System ID and Dataplate’ and go to ‘Calibration Information’. If the Software Phase is earlier than shown below, recalibrate the ECM using the January 2006 INCAL? CD-ROM, or later. Engines with the Software Phase listed below or later do not require a recalibration.

ISX engines with CM870 (engines built after January 2004) require Software Phase 06050302.

ISX engines with CM870 (engines built before January 2004) require no changes at this time.

This is a warrantable calibration change.

Possible causes of this fault are EGR valve motor (+) or (-) leads shorted to ground in the harness, EGR valve motor, or ECM. The ECM monitors the voltage level of this circuit and logs a fault code if the voltage level indicates that a short to ground is present. This fault is always set inactive when the keyswitch is turned ON. If the fault condition reoccurs while the keyswitch is turned ON, the fault code will be set active. Because active faults are set inactive at keyswitch ON, this troubleshooting tree must be used to troubleshoot active and inactive faults.

This also means the only sufficient way to make certain the repair is complete is to run the INSITE? electronic service tool EGR valve test. Operating the engine is not adequate to verify the correct component was repaired or replace.

Possible repairs:

1)Replace the EGR valve assembly.
2)Repair or replace the EGR valve extension harness.
3)Repair or replace the engine harness.