Case IH 3377 – Engine Control Module (ECM): Constant Engine RPM Switch Detected but Option Not Enabled

The Engine Control Module (ECM) is receiving an electrical signal indicating that the Constant Engine RPM (CERPM) switch has been pressed or activated. However, the software configuration within the ECM or Vehicle Control Module (VCM) does not have the Constant Engine RPM feature enabled. This mismatch between the physical switch signal and the software configuration triggers the fault code.

• Magnum Series
• Puma Series
• Maxxum Series
• Farmall Series
• Quantum Series
• Steiger Series

1. 1

   Verify if the tractor was actually factory-equipped with the Constant Engine RPM feature (usually located on the right-hand console or armrest).

2. 2

   Check the tractor's configuration menu (via the AFS Pro monitor, H-Menu, or Electronic Service Tool) to see if the CERPM option was accidentally turned OFF or disabled during a recent software update or calibration.

3. 3

   If the tractor is not supposed to have this feature, check the wiring harness in the right-hand console for a short circuit to power or ground that could simulate a switch press.

4. 4

   Verify if an incorrect switch panel or armrest module was recently installed from a donor tractor that had different options.

1. 1

   Connect Diagnostic Tool

   Connect the Case IH Electronic Service Tool (EST) laptop to the tractor's diagnostic port.

2. 2

   Access Configuration

   Navigate to the Engine Controller (ECM) or Vehicle Control Module (VCM) configuration menus.

3. 3

   Enable the Option (If Equipped)

   Locate the "Constant Engine RPM" (CERPM) setting. If the tractor physically has the switch, change the software setting from "Disabled" to "Enabled". Save the configuration and cycle the ignition key.

4. 4

   Repair Wiring (If Not Equipped / Shorted)

   If the tractor does not have the switch (or if enabling it does not clear the active fault), use a multimeter to trace the CERPM switch circuit in the right-hand console harness. Locate and repair any pinched wires or short circuits.

5. 5

   Replace Faulty Switch

   If the wiring is intact but the switch is internally shorted (sending a constant rogue signal), replace the switch or the affected armrest switch module.

6. 6

   Clear Codes

   Clear fault code 3377 using the EST and test operate the machine to ensure the code does not return.