Case IH F68 – Transmission Controller / FNRP Module: Shuttle Lever Reverse Switch Input Voltage Low

The reverse switch input signal coming from the shuttle lever (or FNRP module) is either shorted to ground or has an open circuit, preventing the controller from verifying that the operator has selected reverse.

• MXM
• Case IH MXM Series
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Case IH Maxxum Series
• Case IH MX Series

1. 1

   Cycle the shuttle lever back and forth (Forward to Reverse) to release potentially stuck mechanical switches, or try traveling in the opposite direction to see if the code clears.

2. 2

   Inspect the wiring harness leading from the shuttle lever / FNRP module on the steering column to the transmission controller for pinched wires (short to ground) or broken wires (open circuit).

3. 3

   Unplug the shuttle lever switch and use a multimeter to test the switch's continuity when shifted into reverse.

4. 4

   Verify if the 5V reference signal is reaching the shuttle lever switch.

1. 1

   Disconnect Power

   Disconnect the tractor's battery before servicing electrical components to prevent further shorts.

2. 2

   Access the Switch

   Remove the steering column covers or console trim to access the base of the Forward/Reverse shuttle lever.

3. 3

   Inspect and Replace

   If the wiring harness is intact but the switch fails the continuity test, remove the retaining pins/screws holding the shuttle lever switch assembly in place and disconnect the harness. Install the new shuttle lever switch.

4. 4

   Reassemble

   Reconnect the wiring harness and reinstall the column covers.

5. 5

   Recalibrate the Transmission

   Perform a Transmission/EDC Calibration (Mode HA calibration) to ensure the controller recognizes the new switch's voltage parameters.