Case IH 19837 – Engine Control Module (ECM / ECU): SCB error on the Turbocharger PWM output powerstage.

The engine control module has detected that the Pulse Width Modulation (PWM) output circuit—which controls the turbocharger actuator (wastegate or Variable Geometry Turbocharger/VGT actuator)—is shorted to battery voltage (typically 12V or 24V depending on the system).

• Tier 4b
• Puma
• Optum
• Magnum
• Maxxum
• Farmall Pro
• N-Series Tractor Loader Backhoes

1. 1

   Harness Inspection: Visually inspect the engine wiring harness routing between the Engine ECU and the turbocharger actuator. Look for melted wire insulation caused by proximity to the hot exhaust manifold or turbocharger.

2. 2

   Voltage Check (Short to Battery Test): Disconnect the turbocharger actuator connector and the Engine ECU connector. Turn the key to the ON position. Measure the voltage on the PWM signal wire at the actuator harness connector. If battery voltage is present, the wiring harness is shorted to a power wire.

3. 3

   Actuator Internal Short Test: If the harness tests good (no voltage on the signal wire when disconnected), check the resistance/continuity of the turbocharger actuator itself to see if it has failed internally and is bridging the power and signal circuits.

4. 4

   ECU Pin Inspection: Inspect the ECU pins for corrosion, bending, or internal shorts.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Repair the Harness

   If the diagnostic checks revealed a short in the wiring harness, locate the damaged section (often near the turbo heat shield). Splice and heat-shrink the damaged wires, or replace the engine wiring harness entirely if the damage is extensive.

3. 3

   Replace the Actuator/Turbo

   If the harness is intact but the actuator is internally shorted, replace the turbocharger wastegate/VGT actuator. Note: On many FPT engines, the electronic actuator is calibrated to the turbocharger and cannot be purchased separately; the entire turbocharger assembly must be replaced.

4. 4

   Reassembly

   Reconnect the actuator and ECU connectors. Ensure the harness is routed away from extreme heat sources and secured with zip ties.

5. 5

   Clear Codes

   Reconnect the battery. Use the CNH Electronic Service Tool (EST) to clear the inactive 19837 fault code.

6. 6

   Test Run

   Start the engine and run it under load to verify the turbocharger actuator is responding to PWM commands and the code does not return.