Case IH 3347 – Engine Control Unit (ECU): Multiple State Switch

The engine controller is receiving an implausible, continuously high voltage signal from this multi-position switch input (Above Range Max / Short-circuit to Battery).

• Case IH Magnum 235 - 340 (Series 4)
• Case IH Steiger series
• Case IH Puma series (165, 180, 195, 210, 225)

1. 1

   Identify which multiple state switch is triggering the fault (commonly the hand throttle position switch or torque reducer switch on the armrest console).

2. 2

   Inspect the wiring harness between the switch and the Engine ECU for chafed insulation, pinched wires, or melted loom that could cause the signal wire to short to a 12V or 5V power source.

3. 3

   Disconnect the switch and inspect the connector pins for corrosion, moisture ingress, or bent terminals.

4. 4

   Using a multimeter, test the signal wire for a short to battery voltage.

5. 5

   Verify that the dedicated ground circuit for the switch (e.g., Pin 25 on some FPT EDC connectors) has good continuity to the ECU ground.

1. 1

   Disconnect power

   Turn off the tractor's key switch and disconnect the battery to prevent electrical damage.

2. 2

   Access the switch

   Access the Multiple State Switch (refer to your specific model's cab/armrest teardown procedure to access the switch panel).

3. 3

   Disconnect harness

   Disconnect the electrical harness from the switch.

4. 4

   Repair wiring harness

   If the wiring harness tested faulty (shorted to power), repair the damaged section of the wiring loom and apply heat-shrink tubing.

5. 5

   Remove faulty switch

   If the wiring tests good, the switch itself has failed internally (shorted contacts). Remove the retaining hardware and extract the faulty switch.

6. 6

   Install replacement switch

   Install the replacement Multiple State Switch and secure it in the console.

7. 7

   Reassemble components

   Reconnect the electrical harness and reassemble the cab trim.

8. 8

   Reconnect battery

   Reconnect the battery.

9. 9

   Clear fault code

   Turn the key ON and use the EASy diagnostic tool (or the tractor's onboard display) to clear the inactive 3347 fault code.

10. 10

    Test functionality

    Test the switch's functionality (e.g., cycle the hand throttle or torque reducer) to ensure the code does not return.