Case IH 3348 – ECU: Multiple State Switch

Fault code 3348 indicates that the Engine Control Unit (ECU) is receiving an implausible signal, an open circuit, or a short circuit from a multiple state switch input. This is typically associated with the Constant Engine Speed (Cruise Control) switch or the Multi-Function Handle on the operator's armrest, which can disrupt engine speed control and related operations.

• Case IH Magnum 235 – 340 (Series 4)
• Case IH Steiger and STX Series (e.g., 280, 330, 380, 430, 480, 530)
• Case IH Puma and Maxxum Series

1. 1

   Verify if the fault is active or stored by clearing the code and actuating the Constant Engine RPM switches and Multi-Function Handle buttons

2. 2

   Physically inspect the Constant Engine Speed switch and the Multi-Function Handle for sticking buttons, physical damage, or liquid intrusion

3. 3

   Inspect the wiring harness between the Engine ECU and the switch, specifically checking circuits 6427 and 6428 for continuity

4. 4

   Use a multimeter to test the switch circuits for a short to ground, a short to battery, or an open load

5. 5

   Disconnect the switch and ECU connectors to check for pushed pins, corrosion, or moisture

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Switch

   Locate the faulty switch on the armrest console (either the Constant Engine Speed rocker switch or the Multi-Function Handle assembly).

3. 3

   Disconnect

   Carefully remove the trim panels surrounding the armrest controls and disconnect the electrical harness from the switch/handle.

4. 4

   Test/Replace

   If the wiring harness passed the diagnostic continuity checks but the switch fails to change states on a multimeter, the switch itself has failed internally. Remove the mounting hardware and extract the faulty switch.

5. 5

   Install New Part

   Install the replacement switch or handle, secure the mounting hardware, and reconnect the electrical harness.

6. 6

   Reassemble and Test

   Reinstall the armrest trim, reconnect the battery, and turn the key on.

7. 7

   Clear Codes

   Use a diagnostic tool to clear the 3348 fault code. Start the engine and test the Constant Engine Speed / Multi-Function Handle to ensure proper operation without the code returning.