Case IH F67 – Transmission Controller: Shuttle Lever Forward Switch Input Voltage High

The forward switch input from the shuttle lever (FNRP module) sends a voltage signal to the controller that is higher than the expected normal range. This typically indicates that the circuit is shorted to a +12V power source, shorted to the module's 5V reference line, or has an open circuit.

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

1. 1

   Cycle/rotate the shuttle lever back and forth between Forward, Neutral, and Reverse to release any potentially stuck internal switch contacts.

2. 2

   Inspect the wiring harness running from the steering column shuttle lever (FNRP module) to the transmission controller. Look for pinched wires, chafing, or exposed copper that could cause a short to +12V or the 5V reference line.

3. 3

   Disconnect the shuttle lever switch and test the forward switch pins for continuity. Verify if the switch is internally shorted or if there is an open circuit.

1. 1

   Disconnect Power

   Disconnect the tractor's battery to prevent electrical spikes during repair.

2. 2

   Access the Switch

   Remove the steering column shrouds/dash panels to access the base of the shuttle lever (FNRP module).

3. 3

   Inspect and Repair Wiring

   If the diagnostic checks revealed a short or open circuit in the wiring harness, repair the damaged section of the wire and secure it with heat shrink and loom.

4. 4

   Replace the Switch

   If the wiring is intact but the switch failed the multimeter test, remove the mounting hardware for the shuttle lever assembly and install a new unit.

5. 5

   Reassemble and Power Up

   Reconnect the electrical connector, reinstall the steering column shrouds, and reconnect the battery.

6. 6

   Clear Codes and Calibrate

   Start the tractor and verify if the code is cleared. In some cases, replacing transmission control components requires a transmission calibration. To enter calibration mode on MXM series tractors, hold the High and Low range buttons and start the engine until 'CAL' appears on the transmission display, set engine speed to 1200 RPM, and follow the on-screen prompts.