Cummins ISB4.5 CM2150 Fault Code: 2351 PID: SID 146 SPN: 2791 FMI: 4 EGR Valve Control Circuit – Voltage Below Normal or Shorted to Low Source.

Circuit Description
The engine control module (ECM) controls the EGR valve, opening and closing it based on various operating conditions. The EGR valve is opened and closed by a DC motor that receives voltage from the ECM on the EGR valve motor signal (+) and (-) circuits. To open the valve, the motor receives voltage on the EGR valve motor signal (+) circuit. To close the valve, the motor receives voltage on the EGR valve motor signal (-) circuit.

Component Location
The EGR valve is located on the exhaust side of the engine and is attached to the EGR cooler, which is mounted to the exhaust manifold.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position and the engine is operating.

Conditions for Setting the Fault Codes
The electronic control module (ECM) detects a short circuit to ground in the EGR motor supply circuits.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
-The EGR valve operation will be disabled.

Conditions for Clearing the Fault Code
-The fault code will always be inactive at key ON. To validate the repair, start and idle the engine for 1 minute. If the fault code does not become active again, the repair has been validated.
-The ECM will turn off the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and passes.
-This fault code can also be cleared with INSITE ™ electronic service tool.

Shop Talk
The ECM monitors the voltage level of the circuit and logs a fault code if the voltage level indicates a short to ground. This fault is always set inactive when the keyswitch is turned ON. If there is a failure of this circuit, the fault code will not be set active until the valve has been actuated. For these reasons, this troubleshooting tree must be used of both active and inactive fault codes.

Possible causes of this fault are EGR valve motor output (+ or -) leads shorted to ground in the harness, EGR valve motor, or ECM.

NOTE: Do not supply 12-VDC to the EGR valve position sensor, or short the EGR valve motor wires to the EGR valve position sensor. The EGR valve position sensor is rated at 5-VDC, and sensor damage may occur