Case IH F66 – Transmission Controller: Shuttle Lever Forward Switch Input Voltage Low

The forward switch input signal coming from the FNRP (Forward/Neutral/Reverse/Park) module or shuttle lever is either shorted to ground or has an open circuit.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Maxxum 100
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 140
• MXU 100
• MXU 110
• MXU 115
• MXU 120
• MXU 125
• MXU 140
• MX80C
• MX90C
• MX100
• MX110
• MX120
• MX135
• MX150
• MX170

1. 1

   Cycle the shuttle lever to release potentially stuck internal switch contacts, or try commanding travel in the opposite direction

2. 2

   Check the wiring harness between the FNRP module/shuttle lever and the transmission controller for an open circuit or a wire shorted to ground

3. 3

   Inspect the harness connectors at the base of the shuttle lever for loose connections or corroded terminals

1. 1

   Disconnect Power

   Disconnect the tractor's battery before starting the repair to prevent electrical shorts or unintended transmission engagement.

2. 2

   Access the Switch

   Remove the steering column or console trim required to access the base of the shuttle lever.

3. 3

   Document Wiring

   Take a clear photo of the wire positions and connectors before disconnecting them. These switches often feature multiple connectors that are easy to mix up during reassembly.

4. 4

   Clean and Inspect

   Clean all electrical connections. If the wiring harness is damaged (causing the short to ground or open circuit), repair the wiring.

5. 5

   Replace the Switch

   If the wiring is intact but the switch has failed internally, remove the mounting hardware and install the new shuttle lever/FNRP switch assembly.

6. 6

   Test

   Reconnect the battery and test the shuttle operation in both forward and reverse directions before reinstalling the trim panels.

7. 7

   Transmission Calibration

   If the shift quality has deteriorated, or if the transmission controller memory was reset during the repair, you may need to perform a Transmission/EDC Calibration.