Case IH 3510 – Engine Control Module (ECM) or Dosing Control Unit (DCU) / Aftertreatment Control Module: SRC low on duty cycle

The duty cycle (PWM signal) for the SCR system's DEF supply module/pump is operating below the minimum allowable limit. This is caused by a failure in 'Sensor Supply Voltage 2' (ECU Power Stage 2) dropping below normal voltage or shorting to ground, which disables emissions dosing.

• Puma
• Optum
• Magnum

1. 1

   Check the main battery voltage and ensure the ECM is receiving the correct voltage supply.

2. 2

   Inspect the electrical wiring harness and connectors between the ECU and the SCR Supply Module for corrosion, chafing, or damaged pins.

3. 3

   Use a multimeter to test the 5V Sensor Supply 2 circuit for a short to ground or an under-voltage condition.

4. 4

   Use a CNH Electronic Service Tool (EST) to monitor the DEF pump motor's internal duty cycle to confirm it is reading below the minimum limit.

1. 1

   Verify Codes

   Connect a diagnostic scanner to verify if code 3510 is active, and check if any other 5V reference codes or SCR codes are present.

2. 2

   Isolate the Short

   If the 5V Sensor Supply 2 circuit is pulled low, disconnect the sensors on this circuit one by one (including SCR pressure/temperature sensors). If the voltage returns to 5.0V upon disconnecting a specific sensor, that sensor is internally shorted and is the culprit.

3. 3

   Harness Repair

   If disconnecting sensors does not restore the 5V supply, trace the wiring harness back to the ECM (specifically the Power Stage 2 pins) to locate and repair any chafed or grounded wires.

4. 4

   Module Replacement

   If the wiring and 5V supply are perfectly intact but the SCR duty cycle remains too low, the SCR supply module (DEF pump) has an internal failure and must be replaced.

5. 5

   System Reset

   Clear the fault codes using the diagnostic tool and run an SCR system test or a forced stationary regeneration to verify the repair.