Case IH 2379 – Transmission Control Module (TCU) or Armrest Controller (ARU / ICP): Parking lock switch - Voltage too high

The control module is receiving a voltage signal from the Parklock switch circuit that exceeds the maximum expected threshold. This typically indicates a short-to-power in the wiring harness, a failed switch internally shorting to a voltage source, or an open circuit on a pull-up sensor line causing the module to see full reference voltage.

• Puma/Mid Range Magnum
• Puma Series
• Magnum Series
• Maxxum Series

1. 1

   Verify battery health and voltage (a dead, low, or recently disconnected battery is a highly common culprit for Electronic Park Lock faults)

2. 2

   Check the clutch pedal switch by listening for a 'click' when pressing the pedal to the floor (a misadjusted screw can fail to trigger the switch and interfere with the park-lock release)

3. 3

   Inspect the wiring harness leading to the F-N-R-P shuttle lever on the steering column or right-hand armrest for pinched wires or chafing that could cause a short-to-battery voltage

1. 1

   Hold brake pedals

   Sit in the operator seat and hold both brake pedals down simultaneously.

2. 2

   Release hand brake

   Release the hand brake.

3. 3

   Turn ignition to RUN

   Turn the ignition key to the RUN position (do not start).

4. 4

   Shift to Neutral

   Place the shift lever in the Neutral position.

5. 5

   Press Neutral button

   Press the Neutral button on the shifter handle. The brake should release and the code should clear.

6. 6

   Disconnect battery

   If reinitialization fails, disconnect the negative battery cable to prevent further electrical shorts.

7. 7

   Remove trim

   Remove the plastic cowling/trim around the steering column (or the right-hand armrest console, depending on where the shuttle lever is mounted).

8. 8

   Locate switch

   Locate the Parklock switch, which is situated under the reverse shuttle lever.

9. 9

   Test switch

   Disconnect the electrical connector and test the switch with a multimeter for continuity. If it is internally shorted, it must be replaced.

10. 10

    Remove hardware

    Remove the retaining hardware for the switch (or the entire shuttle lever assembly, as the switch is often integrated into the F-N-R-P lever).

11. 11

    Install new switch

    Install the new switch/lever assembly and reconnect the wiring harness.

12. 12

    Reassemble cowling

    Reassemble the steering column cowling.

13. 13

    Reconnect battery and calibrate

    Reconnect the battery and perform the EPL Reinitialization Procedure (steps 1-5) to calibrate the new component.